Marcus Morris added 16 points and 10 rebounds off the bench. Al Horford had nine points and five blocks.

The Celtics survived a lethargic start and rough shooting night but rallied to lead by as many as 18 in the second half.

Boston won despite shooting just 43 percent (42 of 97) from the field and 30 percent from the 3-point line (11 of 37). But the Celtics’ struggles didn’t dampen the mood inside TD Garden for the return to regular-season action for Gordon Hayward and Kyrie Irving.

Joel Embiid led the 76ers with 23 points and 10 rebounds. Ben Simmons finished with 19 points, 15 rebounds and eight assists.

Hayward played in his first game since undergoing surgery and more than 10 months of rehabilitation for the gruesome left ankle injury he suffered five minutes into last year’s season opener.

He received an extended ovation from the home crowd during a pregame introduction that included a video montage of his rehab process.

Irving was also back following a pair of surgeries on his left knee that caused him to miss the end of the regular season and playoffs.

They shot a combined 6 for 26 for the game. Hayward finished with 10 points and five rebounds in 25 minutes. Irving had seven points and seven assists.

Including the playoffs, Boston has now won 10 straight games at home over Philadelphia, which it defeated in the Eastern Conference semifinals last season.

Boston got some distance in the second half thanks largely to its bench, which outscored its Philadelphia counterparts 44-26.

After receiving loud ovations during pregame introductions, Irving and Hayward both had sluggish starts.

Hayward missed his first four shots before making back-to-back jumpers. Irving missed his first nine attempts from the field. He didn’t score until finally connecting on a pair free throws early in the third quarter.

Play was sloppy all around in the first half.

The Celtics missed seven of their first 10 shots and the Sixers started just 4 for 11.

The ball also pinballed around the floor at times, with both teams having trouble keeping possession. The Sixers were the most careless, committing 11 first-half turnovers that led to 10 Celtics’ points.

TIP-INS

76ers: Outscored the Celtics 50-34 in the paint. … Jerryd Bayless (left knee), Wilson Chandler (strained left hamstring), and Mike Muscala (sprained left ankle) all sat out.

Celtics: Outrebounded the 76ers 55-47.

UP NEXT

76ers: Host the Bulls on Thursday.

Celtics: Visit the Raptors on Friday.