Despite a solid first three quarters, the C's ran out of steam in the final 12 minutes, and the energetic young Sixers streaked to victory behind the solid bench play of Marreese Speights and Lou Williams.
Speights finished with 19 points, Williams had 16, and the Sixers earned their first win of the preseason.
Nate Robinson poured in a game-high 26 points and Glen Davis added 14, but it wasn't enough for the Celtics, who endure their first loss.
Fourth quarter, 4:20, Sixers 96-81: OK, this one's just about over. Barring an endless barrage of Nate Robinson 3s, the Celtics are headed for their first loss of this preseason.
The Celtics' 10-man rotation started strong, but outlasting a full-strength Sixers club wasn't in the cards.
Fourth quarter, 5:25, Sixers 91-79: The Sixers have looked electrifying in this fourth quarter, with Lou Williams and Marreese Speights running and gunning all over the place to build up a double-digit lead.
The Sixers are now 8-for-10 from 3-point range as a team. The Celtics are 6-for-9. When both teams are this hot, anything can happen — but Philly appears to have a comfortable edge at the moment.
Fourth quarter, 7:54, Sixers 82-75: Do the math — it's now a 24-9 run for the Sixers, who have just demolished the Celtics since Nate Robinson and Glen Davis shut it down late in the third quarter.
If Doc Rivers wants to win this game (which he probably doesn't), then he needs Shrek and Donkey back on the floor.
Fourth quarter, 9:47, Sixers 78-73: The Sixers are on a 7-2 run. Marreese Speights is bringing tremendous energy off the bench for the Sixers — he's their Glen Davis.
If only the Celtics had a Glen Davis type that could step up in crunch time.
Fourth quarter, 10:33, Sixers 76-71: Marreese Speights and Jason Kapono knock down two jumpers in the span of 22 seconds, thrusting the Sixers back into the lead.
Doc Rivers calls a timeout. Time for him to inject some ubuntu into this bench unit. Right now, they're lacking it.
End of third quarter, Sixers 71-69: The Sixers have managed to close the third quarter on a 13-3 run, erasing the Celtics' lead in the blink of an eye.
If the C's want to reclaim this game in the fourth quarter, it's going to take more than just a couple clutch jumpers from Nate. They've got to work together to get stops, which is something these backups haven't done very well tonight.
All these guys are working hard to chase their own numbers, proving their worth to Doc Rivers this preseason. But the best way for these bench guys to prove themselves is to win together.
Can they do it?
Third quarter, 2:05, Celtics 66-62: The Sixers have quietly chipped away at Boston's lead, moving it back to four with a solid offensive effort from Andre Iguodala and Andres Nocioni.
The Celtics have been letting the Sixers attack the basket and score in this third quarter. Semih Erden is having a little bit of an off night — not just because of his zero points and only two rebounds, but he's also not the same rim-protecting presence he was in his debut against these Sixers last week.
The C's still have the lead, but it doesn't feel safe.
Third quarter, 4:52, Celtics 61-52: Jermaine O'Neal checks out, having picked up his third personal foul. J.O.'s stat line at the moment: two points, 12 rebounds. Talk about knowing your role.
The C's aren't looking to their younger O'Neal to be a dominant scorer, and O'Neal is humble enough that he can easily set aside his own scoring and get the job done on the glass.
We knew he'd be good, but 12 boards in 19 minutes is insane. And the guy he's up against is no slouch, either. Elton Brand is a two-time All-Star.
Third quarter, 7:22, Celtics 56-49: Nate Robinson is killing it out there. Another 3, putting the Celtics back up by seven, and Nate now has 18 points. He's shooting an impressive 3-for-5 from long range.
The Sixers only wish they had a bench scorer like Nate among their ranks. He's everything Lou Williams wishes he could be.
Third quarter, 9:28, Celtics 53-46: Two-plus minutes into the third quarter, the Sixers have yet to find the bottom of the net. It's a 6-0 run to open the second half for the Celtics, who now have their biggest lead of the night.
Jermaine O'Neal, Nate Robinson and Glen Davis have each scored once since the break. The Sixers' starters look gassed.
Halftime, Celtics 47-46: Half of this ballgame is in the books, and so far, the Celtics' bench has done a tremendous job of hanging with the Sixers' full-strength roster.
Nate Robinson has 13 points, Glen Davis has eight, and Luke Harangody has eight as well for the C's, who take a one-point lead into the locker room at halftime despite resting all their starters.
Louis Williams leads the way with nine points off the bench for the winless Sixers.
You have to wonder how much urgency this Philly team will show in the second half. These exhibition games might not count, per se, but it would be a huge blow to their pride to start 0-4 in this preseason.
Second quarter, 2:52, Celtics 44-42: The sad thing is that the Sixers are giving their starters heavy minutes, and the Celtics' second and third units are schooling them.
Elton Brand and Thaddeus Young are playing playoff-type minutes, and they've got eight points and seven respectively. Meanwhile, nobodies like Luke Harangody and Stephane Lasme are lighting it up for the Celtics.
There might not be another team in the NBA with the kind of depth that Doc Rivers' Celtics can boast. From one to 17, these guys can ball.
Second quarter, 3:37, Celtics 43-39: Luke Harangody isn't a high-volume shooter, but when he takes them, he makes them count.
Harangody makes back-to-back 3-pointers here to give the Celtics the lead. He's now 3-for-3 from the field, and he's scored Boston's last eight points.
Talk about efficiency.
Second quarter, 5:35, Sixers 35-33: Nate Robinson is the first player to crack double figures tonight, knocking down a beautiful wing 3 to give him 11 points for the night. He's 3-for-6 from the field, including 2-for-3 from long range.
This game will be a good chance for the Celtics' second unit to find its identity. Who's the first option offensively? Is it Nate, or is it Big Baby? Or does it depend on matchups?
Against this Sixers team, with Brand and Speights giving them a lot of size down low, Nate's jump shot is probably the C's greatest weapon. Things might look different against a softer team.
Second quarter, 7:36, Sixers 32-28: Mario West just entered the game, and he's already made his presence known in a big way, making a LeBron James-style "chasedown" to stuff a Jodie Meeks layup. West is playing hard.
Mario West's quest to make this team is one of the more underrated storylines of the Celtics' preseason. The guy brings tremendous energy to this Celtics bench, on both ends of the floor. Doc Rivers mainly talks about him as a defensive stopper, but he can slash to the basket and score, too. Good all-around player.
Second quarter, 8:56, Sixers 30-28: Avery Bradley doesn't look anything like a 19-year-old kid playing his first NBA game. He looks confident and poised — and he just scored his first two points of this preseason.
Two points, two rebounds, one assist and countless energetic defensive plays. Not a bad first few minutes to Bradley's career.
End of first quarter, Sixers 25-21: Avery Bradley has made his entry, and man, that kid is playing hard.
The first thing you notice about Bradley — he's an incredibly hard-working defender. His first possession, he picks up Louis Williams before halfcourt and harrasses him for the ball nonstop; the Sixers through a pick at him, and he bounces off and sticks to Williams like glue.
The guy is hungry. He's been sitting on the sidelines for months, waiting for his chance, and now he's making the most of it.
First quarter, 2:37, Sixers 18-16: It's never too early in the game — or in October, for that matter — for a silly little spat to spill over into double technicals. Nate Robinson and Marreese Speights get whistled here.
Maybe Nate cares about these preseason games more than his elder Celtic teammates. You don't see Kevin Garnett getting T'd up too much in meaningless exhibition contests, do you?
First quarter, 3:49, 16-16: Glen Davis is capable of being a dangerous weapon for the C's when left open. But at the moment, he's forcing it a bit too much.
The C's need to get their 3-point shooters — Robinson, Wafer, Daniels — to turn it on. That'll space the floor a little bit and keep Davis from getting his shot blocked so easily.
Marquis Daniels may have taken a thousand threes every day this summer, but he's taken zero tonight.
First quarter, 5:47, Sixers 12-11: The Celtics may not have their starters, but Glen Davis is more than happy to trade baskets with Andre Iguodala. The C's are keeping this thing close early.
Big Baby has had a big impact this preseason — he's their leading scorer, with 12.0 points per game. Without the Big Three hogging the spotlight, Baby's numbers will only get bigger.
First quarter, 7:04, Sixers 8-7: Jermaine O'Neal doesn't look like a scoring threat out there, but he sure can rebound. The C's center has already grabbed four boards on the defensive end.
Brand has four points, and Thaddeus Young two for the Sixers. They've got a strong interior presence.
First quarter, 9:25, Celtics 3-2: The Sixers are playing hard on the defensive end. They're making every possession difficult for the C's. Elton Brand has already stuffed Jermaine O'Neal twice.
With Brand and Andre Iguodala on the floor, this is an entirely different Sixers team from the one we saw last week.
First quarter, 10:49, Celtics 2-0: Von Wafer is playing for his job, and it shows. The C's shooting guard is attacking the basket early and often.
Expect to see big numbers from Wafer tonight. He might need them if he wants to earn a spot in Doc Rivers' rotation.
7 p.m.: You're wondering how the Celtics' rotation looks when the entire starting five rests? Well, here's how.
Here's your starting five: Jermaine O'Neal, Glen Davis, Marquis Daniels, Von Wafer, Nate Robinson.
Semih Erden, Luke Harangody, Stephane Lasme and Mario West will come off the bench, and Avery Bradley is likely to make his debut tonight as well.
It's a short rotation, but now's the right time for that. This will be Doc Rivers' chance to take a long look at his bench role players.
6:50 p.m.: Tonight might be the night that we finally see Avery Bradley.
The Celtics have been extremely cautious all summer with their first-round draft pick, but Bradley has waited over three months now to make his return from ankle surgery, and he just might be ready.
With the starters resting and Doc Rivers' pool of available bodies drying up, this would be the perfect opportunity to give the former Texas Longhorn some run and see what he can do.
6:30 p.m.: OK, so about that "starting five" thing … change of plans.
The C's will be resting their starters tonight, with another road contest looming tomorrow against the Knicks. Delonte West, who's battled back spasms lately, is also expected to sit.
Tonight might be a good chance to examine the Celtics' fringe guys — Stephane Lasme, Von Wafer, Mario West. With an increase in available minutes, the C's youngsters at the end of the bench will have chances to prove themselves.
5 p.m.: We already know that Shaquille O'Neal won't be able to go tonight, what with the arthritic hip. This contest might be a good chance to see the C's best five-man unit in action: Rajon Rondo, the Big Three, and Jermaine O'Neal at center.
The Celtics' starting lineup changes a lot with Jermaine on the floor instead of the other O'Neal. J.O. isn't as good a scorer, but he has the mobility and the defensive instincts to keep opposing offenses out of the painted area.
Last time these two teams met, the Sixers were forced to become jump shooters. This time around, the problem might get even worse for Philly.
4 p.m.: While we're on the subject of young international centers that had big performances at Worlds this summer, here's some news on Timofey Mozgov.
The 24-year-old Russian big man has won the starting center job for the Knicks, beating out Ronny Turiaf to win the prized role in Mike D'Antoni's rotation this season. His first appearance in the starting job might just be Wednesday night, when he takes on Shaquille O'Neal and the Celtics.
The rookie against the Diesel. That'll be fun.
3 p.m.: Here's an interesting tidbit on Celtics backup Semih Erden: The young center may be paid modestly for his rookie season in the NBA, making under half a million dollars, but he recently raked in a healthy chunk of change on the side.
Erden received a bonus of one million lira, or about $700,000 American, for his role on the Turkish national team at this summer's FIBA World Championships. The Turks came in second, losing in the final round to Kevin Durant's American team, and Erden was a key sixth man for the runner-up.
Not a bad payday for the 24-year-old.
8 a.m.: Last time the Celtics met up with the Philadelphia 76ers, it wasn't even a fair fight.
The C's shellacked the Sixers in their preseason opener last Wednesday in Manchester, N.H., 93-65, putting forth a balanced attack and a dominating defensive effort to cruise to victory. But that Sixers squad was without its two biggest stars, Andre Iguodala and Elton Brand, both of whom should be back in action this time.
The C's travel to Philadelphia for a rematch, which tips off at 7 p.m. Tuesday at the Wells Fargo Center. Iguodala, Brand and the rest of the Sixers will be in hot pursuit of their first win this fall — after the Boston blowout and two losses to New Jersey, they sit at 0-3.
The C's are in the midst of a difficult stretch of five games in seven days. It might be their turn to start resting their stars.