The Lakers are 2-2 since LeBron James returned from a groin injury, which kept him sidelined for about one month. James missed one of those four games for "load management" purposes.
James recorded a triple-double with 28 points, 12 rebounds and 12 assists while Kyle Kuzma added 25 points. Rondo nearly earned a triple-double as well with 17 points, 10 assists and seven rebounds.
Though Rondo hit the game-winning shot, James' all-around effort carried the Lakers.
"I'm starting to get more and more back to myself," James told reporters. "Every possession, every quarter, every time I take a hit, I'm able to nudge it off and keep going. I'm working my way back and I'm getting better and better every single minute."
The Lakers were blown out by 42 points at Indiana before heading to Boston. They also missed out on acquiring All-Star forward Anthony Davis from the New Orleans Pelicans at the trade deadline.
But they were able to rally and win a difficult game against an Eastern Conference contender in the Celtics.
"I think after the deadline, I think they were able to relax," James told the Los Angeles Times of his teammates. "I think it just played a lot with their minds a little bit, and then after the 3 o'clock deadline, we all knew this is who we have and who's going to be around."
The biggest piece coming to the Sixers was forward Tobias Harris, who had 14 points.
Harris' performance in his first game with Philadelphia was especially pleasing to Sixers head coach Brett Brown.
"His personality and his intellect, his basketball intellect stands out," Brown said. "I thought he had some tough defensive plays and down the stretch he had a physicality that might not look from his body ... but gosh, he had some tough plays."
With so many new players trying to mesh with the Sixers, it was unclear how the Sixers would respond.
They seemed to be just fine.
Butler hit all 14 of his free throw attempts and relished the experience of playing with the revamped roster.
"They're always looking to put me in a position to be successful," Butler said. "I think that's the most comfortable thing, knowing that you're going to get the ball in spots that you like to have the ball in. Then, you can go and talk to your teammates, like, 'Hey I'm here, I see this, I see that.' Whenever you're all on the same page on the court, it doesn't matter how many days you've been out there. When you put five guys that can play basketball the right way, the game's really simple."
--Field Level Media