The battle between the Lakers and Celtics was in that 87 victory.
The Lakers have won six of seven against Boston at TD Garden, thanks in part to Kobe Bryant's 27 points and double-doubles by Bynum and Pau Gasol on Thursday.
Bynum totaled 16 points and 17 rebounds, while Gasol added 25 and 14, including a tip-in with 9.8 seconds left in regulation that tied things at 82.
The Celtics, who came in riding a five-game winning streak, failed to get a quality attempt off at the end of the fourth quarter, and missed four shots in the final 70 seconds of overtime.
Ray Allen paced Boston with 22 points and All-Star reserve Paul Pierce added 18 points, nine rebounds and seven assists. Kevin Garnett posted 12 points and 12 boards, but shot just 2-of-13 from the floor after halftime.
Rajon Rondo finished with 14 points and seven helpers, and his floater gave Boston a 79-77 lead with three minutes left in regulation.
Bynum countered with a three-point play, only to have Allen come off a baseline screen and nail one from three-point range with 1:08 on the clock.
After trading misses, Bryant was off on a fadeaway from the left side, but Gasol was there for the tying tip-in with 9.8 seconds showing.
"You just got to play until the clock runs out," Gasol said. "I've been in situations before in my career where you just freeze and you just catch yourself looking at the ball and somebody makes a play and you end up losing a game."
Out of a timeout, Pierce dribbled down the final seconds and was hounded outside the arc before passing to Mickael Pietrus with two seconds left. Pietrus' off-balanced 31-footer was nowhere close to the rim as the buzzer sounded.
"I shouldn't have picked up my dribble. It kind of broke up the play when I picked up my dribble," Pierce admitted.
Pierce drained a three-pointer for an 87-86 lead with 1:51 left in the extra session, and that wound up being Boston's last basket.
Bynum tipped in another Bryant miss at the other end, and Garnett missed jumpers on the next two Celtics possessions. Bryant was off the mark again with 7.9 seconds to play to give the Celtics a chance, but Pierce's forced 18- footer drew iron. Allen was in position for a putback, but Gasol was there to block it away.
"I was in the perfect situation and [Gasol] came out of nowhere," Allen said.
The Celtics were ahead 26-22 after the first quarter and 47-45 at halftime. Bryant scored 12 in the third quarter to give LA a 67-64 advantage heading to the fourth.
The Celtics (17) and Lakers (16) have accounted for 33 of the 65 NBA championships...These two teams will meet again in Staples Center on March 11...The Lakers visit the Knicks on Friday before ending their six-game road trip on Sunday against the Raptors...The Lakers shot just 1-of-15 from three- point range, but won the battle on the glass, 55-45 and outscored the Celtics at the free throw line, 15-5.