On a night when the Celtics had every reason to look lethargic after a four-game trip covering three time zones, and barely enough time to get a hot meal at home before another game, Marcus Smart continued to grind.

After the hard-charging Philadelphia 76ers rallied to take the lead midway through the fourth quarter, Smart pushed back, causing havoc with his relentless defense while his normally inconsistent jumper was splashing.

Smart continued his sparkling play with a career-high eight steals to go along with 21 points, 5 rebounds, and 5 assists as the Celtics won for the 11th time in 12 games with a 116-108 victory at TD Garden on Wednesday night.

This spotty performance was expected after the Celtics played four games in six nights, flying first to Sacramento, and then not arriving back in Boston from Dallas until Tuesday afternoon. Boston committed 23 turnovers, good for 34 Philadelphia points, and the Celtics had no answer at times for Dario Saric (20 points) and high-leaping Everett native Nerlens Noel (16).

Smart, however, played in high gear all evening, pestering the Philadelphia ballhandlers with his aggressive style. And he capped his evening with perhaps his most physical play (that wasn’t called a foul) of the season.

After Noel’s two free throws tied the game at 101 with 5:07 left, Isaiah Thomas (33 points) scored a layup, and Smart added a 3-pointer. Later, Smart (looking like Patriots linebacker Dont’a Hightower) wrestled the ball away from Nik Stauskas and started a fast break, with Jae Crowder scoring an easy layup for a 108-101 lead with 2:55 left.

Stauskas immediately jumped up and complained for a foul. Smart giggled after the game when asked if that play could be considered a strip-sack.

“I don’t know. I saw the ball and went after the ball,’’ he said. “He just happened to be in the way of it.’’

Said Crowder: “Once I saw [Smart take the ball from Stauskas] I started to take off running. He made a hell of a pass to me and even more of a hell of a play to dive on Stauskas and take the ball from him. That was a Marcus Smart-type of play, for sure.’’

While it will be considered just another win over a downtrodden team, the Celtics were especially proud of themselves for their ability to bounce back after a poor first half defensively. Boston forced 15 turnovers in the second half (five steals by Smart) and held Robert Covington and Gerald Henderson (27 combined first-half points) scoreless after halftime.

“I told our guys to stay on Central time and we started playing about an hour late,’’ coach Brad Stevens joked. “Obviously, you could feel in the first three possessions that it wasn’t going to be all that crisp. After that we settled down on offense. We didn’t guard until the third quarter. But you have to grind some out. You have to figure out a way to get some, and I really did tell a couple of those guys the best thing for your body clock is to stay on Central time.’’

The Celtics weren’t exactly thrilled with having to come home from a four-game trip for one game, before heading back out on the road to Chicago for the second half of a back-to-back to end the unofficial first half. The 76ers had won their previous three games, including snapping Miami’s 13-game winning streak, followed by a win at Charlotte.

And they never stopped pushing the Celtics until the waning moments.

Smart finished a plus-22, while Thomas tied John Havlicek’s franchise record of consecutive games with at least 20 points at 40. Thomas sealed the game with 13 points in the four quarter, while Smart helped curtail Philadelphia’s offensive momentum after the 76ers hit their first six shots of the fourth.

In February, Smart is averaging 13.8 points (on 48.1 percent shooting), 4.2 rebounds, 4.7 assists, and 3.2 steals, emerging as an invaluable player.

“I’ve been really trying to elevate my game, especially going into the second half [of the season] trying to keep the momentum alive,’’ he said. “I can honestly say this is the most comfortable I’ve been in a Celtics uniform. It feels good, to be able to contribute to this team in other ways. It’s something I’m going to continue to try to keep going.’’

Just a few weeks ago, Smart was screaming at the coaching staff after being removed late from a game in Washington in which the Celtics had relented. Afterward, he punched a hole in the locker room wall out of frustration. That incident seemed to spark Smart’s resurgence.

“I think the last couple of weeks have been some of his best basketball. And we needed it,’’ Stevens said. “We’re down a couple of bodies and he is playing at a high level on both ends of the floor. And then in the last few weeks I just think, like, he’s really found a rhythm and a groove. And it started on the defensive end with guarding at a really high level. I think he’s guarding even better than he did at the start of the year, and he’s been good. We need him to again.’’

Gary Washburn can be reached at gwashburn@globe.com. Follow him on Twitter @GwashburnGlobe.