David Krejci began the play as he got the puck in the neutral zone off a Nicklas Backstrom giveaway. Krejci got the puck to Milan Lucic, who in turn fed it to Seguin.
Seguin came down the middle, cut to the right and waited for Braden Holtby to go down, then flipped the puck in at the right post.
The Bruins have now evened the series at 3-3 and will return home for Game 7 on Wednesday night at the Garden looking to advance to the second round.
Overtime, 1:54, 3-3: The Bruins threaten again, but Chara can't get the shot on net from the left side as Mike Green and Holtby both come out to challenge him. Dale Hunter uses his timeout as the Caps look a little rattled at the start of overtime.
Overtime, 1:24, 3-3: Milan Lucic goes off with the nifty end-to-end rush but fires wide at the end of the opportunity.
Overtime, 0:00, 3-3: The sudden-death period has begun down there in D.C., where the next goal will determine whether the Bruins live to play another day or not.
Third Intermission Notes: There was much better effort from the Bruins in the third, but they once again could not hold on to a lead as the Capitals answered for the third time in this one.
After being outhit 14-3 in second, the Bruins turned that around in the third for a 12-4 edge of their own. They lead 37-32 overall in that category, with the top defense pairing of Dennis Seidenberg (six hits) and Zdeno Chara (five hits) combining for 11.
Patrice Bergeron continues with his gutsy effort. He has an assist with three shots, two hits, two takeaways and a blocked shot in 18:46. He hasn't been taking faceoffs because of his injury, but took a huge one late, winning the only draw he took in the defensive zone after an icing with 1:02 left to play.
Big game from Andrew Ference as well. he had the go-ahead goal midway through the third and also has an assist, four shots and is plus-2 in 18:52.
End Regulation, 3-3: The Bruins may or may not get to play another game, but they will play another period as this one will go to sudden death after the teams trade goals in the third to remain deadlocked after 60 minutes.
Third Period, 18:58, 3-3: The Bruins ice the puck again, leading to a huge draw in defensive zone. Bergeron takes, and wins, his first faceoff of the game.
Third Period, 16:12, 3-3: Ovechkin nearly strikes again with a blast from the left wing that appeared to clip the crossbar. Thomas may have gotten a piece first.
Third Period, 15:08, 3-3: The Caps answer once again, with Alex Ovechkin scoring the tying goal with less than five minutes left in regulation.
Rich Peverley was again taking the defensive-zone draw for Bergeron, and Nicklas Backstrom won it cleanly to Ovechkin, who kicked it from his skate to his stick and fired a quick shot through Thomas' pads.
Third Period, 11:57, Bruins 3-2: The Bruins pull ahead again as Andrew Ference scores on a rebound in the slot.
Tyler Seguin began the rush after an Alexander Semin turnover. Seguin took the puck away from Semin, charged down the right wing and fired a shot on Holtby as Milan Lucic and David Krejci crashed the net, taking their defenders with them. That left Ference all alone as he followed up the play and banged home the rebound in front.
Third Period, 10:50, 2-2: The Bruins survived more than they killed that penalty. The Caps couldn't convert, but they have have taken over the momentum with that power play.
Third Period, 8:50, 2-2: The Bruins have another big penalty to kill as Benoit Pouliot takes a bad penalty, called for roughing for a high hit as he leapt into Brooks Laich.
Third Period, 7:04, 2-2: The Bruins lead 5-3 in shots so far in the third. They managed just five shots in all of second period, while the Caps had 15.
Third Period, 4:15, 2-2: More of an even start to the third after the Caps controlled most of the second. Both teams with chances in the opening minutes of the final frame.
Third Period, 1:39, 2-2: The Bruins can't convert that power play, and all the penalties are over, with the sides back to 5-on-5.
Third Period, 0:00, 2-2: The final frame is under way, with the Bruins starting on a 4-on-3 power play as they try to extend their season for at least one more game.
Second Intermission Notes: It was an ugly second period for the Bruins, who were ineffective on the power play, outshot 15-5 and outhit 14-3, with Washington finally capitalizing late with the tying goal in the final minute. It's now 2-2, and the Bruins will have to play much better in the next 20 minutes if they want to play any more this season.
The Bruins looked to be making strides on the power play early on, but that ground to a halt when they couldn't get anything going in a four-minute advantage after Alex Ovechkin cut Zdeno Chara with a high stick. That kill gave Washington momentum, and they eventually converted when Jason Chimera tied it in the final minute.
It could have been a lot worse, but Tim Thomas has made some huge saves, none better than the 2011 vintage dive across the crease to rob Marcus Johansson.
Patrice Bergeron keeps gutting it out. He is plus-1 with an assist, a shot and two hits in 12:43, but he has also taken two penalties and is unable to take draws. Rich Peverley is 9-7 in his place there, but the Bruins are clearly missing their best faceoff man as they are 27-29 as a team.
Jordan Caron has been mostly a non-factor in his return to the lineup in place of Shawn Thornton. Caron has played just 3:55 and is a minus-1. He did have a shot and a hit, both coming on one solid shift by the fourth line after Claude Julien used his timeout to try to settle his club.
End Second Period, 2-2: The middle frame comes to a close down there in Washington, where the Caps have some momentum after tying the game late in the second, but the Bruins will still be on a power play to start the third.
Second Period, 19:39, 2-2: Things are getting nasty in Washington. After Benoit Pouliot and Troy Brouwer got matching minors for slashing and roughing, respectively, jostling off a faceoff, Matt Hendricks gets called for tripping, and the Bruins will have a 4-on-3 power play.
Second Period, 19:18, 2-2: The Caps come back to tie it again in the final minute of the second as Jason Chimera scores.
Nicklas Backstrom set it up with a rush down the right wing, sending a backhand pass across to Chimera for the easy tap-in behind Thomas at the left post. Chimera clipped Brad Marchand, knocking him over going by before the goal, but no penalty was called.
Second Period, 17:44, Bruins 2-1: The Bruins survive that penalty despite some strong pressure from the Caps, and the sides are now back at even strength with Bergeron out of the box.
Second Period, 15:44, Bruins 2-1: The Bruins are shorthanded again as Patrice Bergeron high-sticks Alexander Semin. The Caps appeared to have too many men on the ice during the delayed call, but only Bergeron goes to the box as Washington gets the power play.
Second Period, 13:20, Bruins 2-1: The timeout seems to have had an effect, with the Bruins picking up their play. The fourth line takes a rare shift to keep the Caps hemmed in their own zone as the Bruins create several scoring chances.
Second Period, 10:52, Bruins 2-1: Brutal giveaway in front by Johnny Boychuk to Nicklas Backstrom, who passes to Alexander Semin on the left. Semin then finds Marcus Johansson at the right post with a seemingly open net in front of him, but Thomas manages to scramble back across the crease and make a diving stick save to keep the Bruins up by one.
Claude Julien uses his timeout after the play to try to settle down his players as Washington has taken over the momentum completely here in the second.
Second Period, 8:46, Bruins 2-1: Both teams have scoring chances in back-and-forth action — Seguin with a rush that ended with him stuffed at the near right post by Holtby, then the Caps counter with a wild scramble in front of Thomas that ended after Mike Knuble sends a rebound just wide of the net.
Second Period, 5:57, Bruins 2-1: The Bruins can't convert on that chance, which could be a big turning point in this game. The Bruins had just one shot on goal in the four minutes. They did have some pressure late, but the Caps had the best scoring chance early with a 2-on-1 break shorthanded.
Second Period, 1:57, Bruins 2-1: Big opportunity for the Bruins as Alex Ovechkin gets sent to the box for a high-sticking double minor after drawing blood by raking his stick across the bridge of the nose and forehead of Zdeno Chara. The Bruins go on a four-minute power play as Chara gets some repairs on the bench.
Second Period, 1:22, Bruins 2-1: There's a break in the action early in the second as the rink crew down in Washington makes some repairs to the glass.
Second Period, 0:00, Bruins 2-1: The middle frame is under way down in Washington, where the Bruins will look to increase their lead as they try to stay alive in this series.
First Intermission Notes: The Bruins got the start they needed, coming out strong with the first goal of the game, then answering when Washington tied it to take a 2-1 lead into the break.
The Bruins are playing with the desperation they need, outhitting the Caps 22-14 and playing with some needed energy. Maintaining that will be the key going forward, especially without Shawn Thornton in the lineup to provide a spark when needed. That decision could be one of the few missteps Claude Julien has made as Bruins coach. Jordan Caron was a complete non-factor in the first period, playing just 2:02 but still managing to be a minus-1 with no shots and no hits.
Patrice Bergeron is obviously playing hurt. He's not taking faceoffs but is still making an impact. He set up the first goal and has a shot and two hits in 6:37, although he did take a tripping penalty. Rich Peverley is 4-3 on draws taking the faceoffs in Bergeron's place. Peverley has elevated his game overall with a goal and an assist. It's also good to see David Krejci being more aggressive. He leads the Bruins with three shots and drove hard to the net for Boston's second goal off a nice feed from Milan Lucic on the power play.
Mike Mottau played 2:42 in his first game of the series, replacing Joe Corvo. Mottau is a minus-1 with no official shots on goal, but he did send one attempt that clanged off the post.
End First Period, Bruins 2-1: The opening period comes to a close with the Bruins holding a rare lead after an eventful first frame down there in Washington.
First Period, 19:18, Bruins 2-1: The Bruins are able to survive that penalty, with Washington threatening right to the very end when Thomas is just barely able to cover up a loose puck in the crease with Troy Brouwer looking to bang it home.
First Period, 17:18, Bruins 2-1: The Bruins immediately give the Caps a chance to tie it back up as Chris Kelly is called for holding Joel Ward's stick and Washington returns to the power play.
First Period, 16:48, Bruins 2-1: The Bruins convert this power-play chance, taking the lead again as David Krejci scores in front.
Boston came into the zone with speed, with Bergeron colliding with a defender at the blue line. There was no call, and Milan Lucic broke down the left wing and centered to Krejci for the redirection at the top of the crease.
First Period, 16:02, 1-1: The Bruins go back on the power play as Alexander Semin is sent to the box for hooking Andrew Ference.
First Period, 14:54, 1-1: The Bruins had several great chances, with Bergeron firing just wide off the side of the net and Milan Lucic getting stoned in front by Holtby, but they are unable to convert the power play.
First Period, 12:54, 1-1: The Bruins get their first power-play chance of the day as Jason Chimera goes off for hooking. The Bruins are just 1-for-15 on the power play in the series, but they did score on their last chance in Game 5.
First Period, 12:01, 1-1: The Bruins kill off the penalty, but Washington had several good scoring chances as they have definitely taken over the momentum in this one for now.
First Period, 10:01, 1-1: The Caps now go on the power play as Patrice Bergeron takes the first penalty of the game. He heads to the box for tripping, ande Washington has the chance to really grab the momentum in this one.
First Period, 9:47, 1-1: The Caps answer right back, with Mike Green tying the game with a blast from the slot.
Green slid across the middle, showing great patience and holding the shot as Gregory Campbell went down and slid past. Green then finally unleashed the blast, which appeared to hit off Greg Zanon in front and past Tim Thomas.
First Period, 8:50, Bruins 1-0: The Bruins' goal has now been changed to Peverley. It looked like his tip alone was the score all along. Bergeron still gets an assist for a pass back to Ference to set up the shot.
First Period, 5:56, Bruins 1-0: The Bruins do take the early lead as Patrice Bergeron tips in an Andrew Ference shot.
Rich Peverley, still taking faceoffs instead of Bergeron, won the offensive-zone draw, which Bergeron then fed back to Ference for the shot. Peverley appeared to deflect it in the slot, but Bergeron was credited with the goal as he must have tipped it as well before it bounced past Holtby.
First Period, 4:28, 0-0: The Bruins nearly take the lead when Mike Mottau's shot from the right point hits the far post. David Krejci was jamming at the left post but couldn't get a stick on the rebound.
First Period, 1:22, 0-0: Braden Holtby makes a huge save early, denying Tyler Seguin on the backhand after Seguin burst down the middle past Mike Green for the bid.
First Period, 0:00, 0-0: The game is under way down in Washington, where the Bruins will try to stay alive and force a Game 7 back in Boston. Peverley took the opening draw instead of Bergeron, who obviously may not be 100 percent for this one.
3:15 p.m.: Patrice Bergeron is not only playing — he's starting between Brad Marchand and Rich Peverley. Zdeno Chara and Rich Peverley open together on defense with Tim Thomas in goal.
The Capitals counter with Jason Chimera, Jay Beagle and Matt Hendricks up front, Karl Alzner and John Carlson on the blue line and Braden Holtby in net.
3:12 p.m.: The lineups are out, and Patrice Bergeron is in. Joe Corvo is out, though, with Mike Mottau making his series debut in his place.
In a bigger surprise, Shawn Thornton is a healthy scratch. Jordan Caron will pay. Tuukka Rask also returns to back up Tim Thomas. Anton Khudobin, Andrew Bodnarchuk and Adam McQuaid (upper body) are the other scratches.
Jeff Halpern, Mattias Sjogren, Jeff Schultz, Dmitry Orlov, Mathieu Perreault and Tomas Vokoun out for Washington.
3:05 p.m.: Still waiting for official scratches, but Patrice Bergeron did skate in line rushes with Brad Marchand and Rich Peverley, and Joe Corvo took part in skating with Greg Zanon.
Looks like both will indeed play in Game 6, but official lineups are not out yet.
2:50 p.m.: Claude Julien was true to his word, as reports from Washington have Patrice Bergeron, Joe Corvo, Jordan Caron, Mike Mottau and Andrew Bodnarchuk all on the ice for warm-ups. Still have to wait to see who will be in the final lineup, though.
2:40 p.m.: The warm-ups have begun down in Washington. Tim Thomas and Braden Holtby led the teams out and will be the starters in goal as expected.
The bigger news is that reports from Washington have Tuukka Rask also taking warm-ups. He will apparently dress for the first time in the series and back up Thomas.
2 p.m.: During his pre-game briefing moments ago, Claude Julien told reporters in Washington that Patrice Bergeron and Joe Corvo will both take warm-ups, then their status for Game 6 will be determined.
1:55 p.m.: There's just a little over an hour to go before the Bruins will try to stave off elimination in Washington and extend their season for at least one more game back in Boston.
The status of Patrice Bergeron and Joe Corvo is still uncertain after both were injured in Saturday's Game 5 loss at the Garden. The Boston Globe's Fluto Shinzawa, on site at the Verizon Center, reported that Bergeron arrived at the rink on his own before the rest of the team this morning, likely for further evaluation. Shinzawa later said that Corvo arrived on the bus with the rest of the team and added encouragingly that Corvo participated in the pre-game soccer ritual, but also mentioned that Andrew Bodnarchuk traveled with the team for the first time in the series.
8 a.m. ET: The Bruins could be playing their final game of the season Sunday.
Less than 24 hours after dropping a 4-3 decision to Washington in Game 5 at the Garden on Saturday, the Bruins head back to Washington needing a victory in Game 6 on Sunday afternoon at the Verizon Center.
Washington is now in control of the series, leading by a game for the first time with a chance to close out the reigning Cup champs on the Capitals' home ice.
The Bruins will try to draw on their experience from last year's Cup run, when they became the first NHL team ever to win three Game 7s in a single postseason. Their only chance to stay alive this year is to force another Game 7 with a victory Sunday as the Caps are now up 3-2 in the Eastern Conference quarterfinal.
This is a little different than the times Boston staved off elimination last year. They were up 3-2 against both Montreal and Tampa Bay, losing Game 6 on the road each time before returning to the Garden to prevail in Game 7. The only time they were down 3-2 last year was in the Cup Final against Vancouver, and they were able to return to the comfort of home for Game 6 to extend that series.
Now they have win on the road to force a Game 7. They may also have to do it without center Patrice Bergeron and defenseman Joe Corvo, who both were injured in Saturday's loss. The status of both players was uncertain after Saturday's game. Bergeron would be the much bigger loss as he is the club's top defensive forward and one of its best offensive performers as well.
Corvo has struggled at times in his first season with the Bruins, but his absence would be felt as well as the Bruins are already down a defenseman with Adam McQuaid sidelined with an upper-body injury. Mike Mottau would replace Corvo if needed, while Jordan Caron would likely step into the lineup up front if Bergeron can't play. That would require some line shuffling, as Caron is a winger. Someone else, likely Rich Peverley or Brian Rolston, would have to move to the middle to fill the void at center.
The puck drops at 3 p.m. Stay with the NESN.com live blog, as we'll keep you up to speed on everything happening.