Final, Senators 2-1:The Bruins can't get the equalizer in the closing minutes and fall to Ottawa despite a 40-20 edge in shots.
That ends the Bruins' three-game win streak in the preseason, as they fall to 3-1-1 with both losses coming to Ottawa.
The bigger loss could be defenseman Steven Kampfer, who left in the third period with a left knee injury. He will have an MRI on Friday to determine the severity of the injury.
The Bruins will look to close out the preseason on a better note when they play the Islanders in Bridgeport in their final exhibition game on Saturday.
Third Period, 17:58, Senators 2-1: The Bruins are back at full strength, and Horton nearly ties it back up with a chance from the left circle on an odd-man break after Peverley gets out of the box.
Third Period, 15:59, Senators 2-1: The Senators convert on the first half of the power play to take their first lead of the night.
David Rundblad one-timed a blast from the left point that deflects in off Adam McQuaid's stick in front and gets past Thomas.
Third Period, 15:02, 1-1: The Bruins face a big challenge now as Rich Peverley is called for a high-sticking double minor, putting Boston shorthanded for the next four minutes.
Third Period, 14:33, 1-1: The Bruins have a chance to pull back ahead as Daniel Paille breaks in clean behind the defense, only to be denied by Anderson on a pad save. Paille did not get all of that as the shot appeared to go off the heel of his blade.
Third Period, 12:39, 1-1: The Bruins dodge a bullet as Mika Zibanejad appears to give Ottawa the lead, but the goal is waved off for Colin Greening bumped Thomas inthe crease.
There was no penalty for goaltender interefrence with thecontact ruled incidental, but it was enough to wave off the goal.
Third Period, 10:54, 1-1: The Bruins finally get another threat with Krejci driving down the left side and cutting to the middle, but Anderson makes the stop despite Lucic driving the net to distract him.
That's just the fourth Bruins shot this period, while Ottawa has six. The Bruins had a 30-10 edge in that category going into the period.
Third Period, 7:52, 1-1: Not a sight the Bruins wanted to see here in the preseason, as defenseman Steven Kampfer is hurt. He went down awkwardly when hit along the boards by Jared Cowen after pinching in deep into the Ottawa zone.
Third Period, 5:10, 1-1: And after the Bruins failed to convert, the Senators tie it at the other end.
Daniel Alfredsson scores from Colin Greening and this is a whole new game going into the final 15 minutes. Greening intercepted a Thomas pass behind the net and fed it out front to Alfredsson for the goal.
Third Period, 4:59, Bruins 1-0: The Bruins continue to threaten, first with Bergeron with a steal in font that he can't convert and then with Peverley denied point blank in front off a Marchand feed.
Third Period, 0:00, Bruins 1-0: The final frame is under way here at the Garden. The Bruins have dominated so far, but have just a one-goal lead to show for it as they try to extend their preseason win streak to four games.
End Second Period, Bruins 1-0: The Bruins kill off that penalty and Paille nearly has a breakaway coming out of the box, but time expired.
The Senators did reach double digits in shots on that power play, so they have that going for them. The shots are 30-10 in favor of Boston, but the Bruins still have just a one-goal lead after a scoreless second period.
Second Period, 17:53, Bruins 1-0: The penalty-fest continues with Daniel Paille going back to the box, this time for hooking.
Second Period, 16:48, Bruins 1-0: The Bruins are starting to look like their old selves on the power play, as they come up empty on another man advantage.
Second Period, 14:48, Bruins 1-0: Things get a little nasty here late in the second as Nick Foligno boards Zdeno Chara in front of the penalty boxes. That leads to a scrum with Milan Lucic and Zack SMith nearly coming to blows.
Foligno gets the only penalty for boarding, and Chara is OK and stays on the ice for the power play.
Second Period, 12:00, Bruins 1-0: Another power-play chance is squandered, though the Bruins did have several strong scoring chances. The best came from David Krejci in front, but it remains a one-goal game despite a 27-7 shot advantage.
Second Period, 10:00, Bruins 1-0: That power play is short-lived, as David Rundblad is sent to the box for boarding. It will be 4 on 4 for 46 seconds, then the Bruins will go back on the power play.
Second Period, 8:45, Bruins 1-0: The Bruins will be shorthanded now, and without one of their primary penalty killers as Daniel Paille is sent to the box for tripping.
The Bruins have a 25-6 edge in shots, but the Senators can tie this one up with a power-play strike here.
Second Period, 5:10, Bruins 1-0: The Bruins continue to pour shots on Anderson, as they've now outshot Ottawa 23-5. The latest bid came on a Joe Corvo blast after he stole a clearing attempt at the blue line.
Second Period, 2:47, Bruins 1-0: The Bruins can't convert the two-man advantage and the Senators are back at full strength.
Second Period, 0:47, Bruins 1-0: The Bruins will have a two-man advantage for just under a minute as Sergei Gonchar joins Zibanejad in the box for holding.
Second Period, 0:00, Bruins 1-0: The middle frame is under way here at the Garden, with the Bruins still on the power play for the first 1:46 of the second.
End First Period, Bruins 1-0: The Bruins head into the first intermission with a 1-0 lead after dominating most of the opening 20 minutes. They'll also have 1:46 left on their third power play of the night to start the second.
First Period, 19:45, Bruins 1-0: The Bruins will get another chance on the man advantage as Mika Zibanejad is called for delay of game for clearing the puck over the glass.
First Period, 18:52, Bruins 1-0: The Bruins can't convert on that chance, failing to get a shot on goal as their lead in taht category remains 20-5.
First Period, 16:52, Bruins 1-0: The Bruins will get another power-play chance as Rich Peverley draws a holding call on David Rundlund.
First Period, 15:34, Bruins 1-0: The Bruins continue to dominate the game territorially, leading 20-4 in shots. But it remains a 1-0 game as Craig Anderson is keeping the Senators in this one early.
First Period, 10:35, Bruins 1-0: The Bruins contnue to click on the power play as they jump out to an early lead after Milan Lucic strikes on the man advantage.
Lucic converted a feed from Horton on the left side. David Krejci started the play with a pass down to Horton. The Bruins are outshooting Ottawa 18-3 at this point.
First Period, 10:21, 0-0: The Bruins will go on their first power play of the night as Zenon Konopka heads to the box for hooking.
First Period, 9:47, 0-0: Nathan Horton gets in on the hitting, lining up Filip Kuba for a hard check in the corner of the Ottawa zone. Good to see Horton playing with his usual aggressive style after the injuries he suffered in the postseason.
First Period, 7:17, 0-0: Very good tempo to start this one, with the Bruins holding a 6-1 edge in shots,but it remains scoreless.
Lots of hitting early as well, with Steven Kampfer getting the worst of it so far. The Bruins' defense hopeful has been belted by both Chris Neil and Mika Zibanejad already.
First Period, 2:17, 0-0: The Bruins kill off that penalty, and actually had the best scoring chance shorthanded. Daniel Paille deked around David Rundblad and sent a crossing pass to Chris Kelly, but Anderson stopped his bid at the left post.
First Period, 0:17, 0-0: The Bruins find themselves shorthanded quickly, as Lucic is sent to the box for kneeing just 17 seconds into play.
First Period, 0:00, 0-0: And we're under way here at the Garden, with the Bruins playing their final home preseason game against the Senators, who handed them their only exhibition loss this year with a 2-1 overtime decision in Ottawa.
7 p.m.: The Bruins will open with their top line from last year, David Krejci centering Milan Lucic and Nathan Horton.
Newcomer Joe Corvo starts on defense with Andrew Ference, while Tim Thomas is in net.
6:55 p.m.: There are a couple of familiar faces in Ottawa's starting lineup, with former Bruins Sergei Gonchar starting on defense alongside rookie Jred Cowen.
They're playing in front of goalie Criag Anderson, who was also briefly a Bruin, though he never got into a game with Boston, just dressing as Thomas' backup a handful of times.
Up front, the Senators are starting Jason Spezza between Colin Greening and Nikita Filatov.
6:40 p.m.: Based on the drills in warm-ups, the Bruins' line combinations will be the same as at the morning skate:
Scratches will by Shawn Thornton, Tyler Seguin, Lane MacDermid and Max Sauve up front, Dennis Seidenberg and Johnny Boychuk on defense and Anton Khudobin in goal. Tuukka Rask will dress as Tim Thomas' backup.
6:30 p.m.: The teams have taken the ice at the Garden.
Tim Thomas and Craig Anderson led the clubs out. That will be the goaltending matchup to start this one.
6 p.m.: The Bruins will take on Ottawa in just over an hour here at the Garden.
Tim Thomas is expected to get the start in goal, with a roster of mostly regulars playing in front of him. Dennis Seidenberg, Johnny Boychuk, Shawn Thornton and Tyler Seguin are scheduled to be the scratches, but the rest of the lineup will comprise of players who should be on the opening night roster.
If the line combinations from the morning skate hold true, that will include the top line of Milan Lucic, David Krejci and Nathan Horton, who are expected to play together for the first time this preseason, and Rich Peverley again getting a chance to play on the second line with Patrice Bergeron and Brad Marchand.
8 a.m. ET: The Bruins return home for their final Garden tune-up on Thursday, hosting Ottawa in their penultimate preseason game overall.
The Senators put the only blemish on Boston's exhibition record with a 2-1 overtime win in Ottawa last Wednesday. Since then the Bruins have rolled to three straight wins, beating the Islanders 6-3 at the Garden and the Canadiens 7-3 in Halifax and 2-1 in Montreal.
With just Thursday's game against the Senators and a matchup Saturday against the Islanders in Bridgeport left on the preseason schedule, the Bruins don't have a lot of time to fine tune their game and finalize their roster before the real games start next Thursday. That puts a premium on these two final exhibition games.
"With five lines and eight D's, I think we're pretty close to the group that we want to be able to work on the stuff that we want to work on as a team," Bruins coach Claude Julien said after Wednesday's practice. "I still think we have room with those two games to evaluate players, because I mean, most of our team is back, so it's not like we're evaluating 10 new players.
"We've got some spots that are open and there's certain players that we want to have a better look at and we've got that opportunity," Julien continued. "I think our guys, with just having a couple of months off, I don't think they've lost that chemistry. I don't think they've lost much and you can see it out there that they're pretty comfortable with each other whenever you put those guys back as lines so we're going to continue to evaluate."
While the camp roster has been trimmed to 27 players, the competition for the final spots is more intense than ever. Steven Kampfer and Matt Bartkowski are vying for the seventh defenseman role, while Jordan Caron, Chris Clark, Max Sauve and Lane MacDermid are battling for one or possibly two open spots at forward. While the rest of the veterans would appear safe, Julien wants to make sure no one gets too comfortable.
"I think it gets pretty obvious at the end who you're battling against for the most part," Julien said. "At the same time it's good competition. I don't mind that at all, and that doesn't mean that those guys are only fighting for open spots. They can be taking somebody else's spot if we feel that they're a step ahead of them. We got a chance to see some of those guys in the next couple of games and hopefully they'll make our decisions as hard as possible."
The game will be televised on NESN, with the puck dropping at 7 p.m. at the Garden, so check back here for updates on all the action.