The Celtics played most of their starters Saturday night in their first home game of the 2024-25 preseason. Their opponent, the 76ers, played none of theirs.

The result: exactly what you’d expect when the NBA champs face a bunch of backups.

Boston, which started Derrick White, Jrue Holiday, Jaylen Brown, Jayson Tatum and Luke Kornet for the third straight game, battered Philadelphia’s reserves, building a 40-18 lead after one quarter.

The Celtics went on to win 139-89 in front of a boisterous crowd at TD Garden.

The surprise star of Boston’s dominant opening frame was Kornet. The 7-foot-1 center accounted for five of the Celtics’ first six made field goals and 11 of their first 14 points, outscoring the Sixers by himself during that span.

In his 18 minutes, Kornet totaled 15 points — a mark he topped just twice last season — on 7-of-10 shooting. He added eight rebounds and two assists, including one in transition that set up a Tatum corner three.

Kornet typically is third on the depth chart behind Kristaps Porzingis and Al Horford when the Celtics are fully healthy. But with Porzingis recovering from offseason leg surgery and Horford yet to play a minute this preseason, the 29-year-old has seen a spike in playing time and made the most of his larger role. He started each of Boston’s first three exhibition games and played well in all three.

Horford watched Saturday’s win in street clothes. Mazzulla said this week that the 38-year-old is healthy but still “ramping up” as he enters his 18th NBA season.

If the Celtics want to avoid overburdening their oldest player early in the season, would they consider starting Kornet and using Horford selectively off the bench? Mazzulla didn’t shoot down that idea when asked about it Thursday, saying he’ll do “whatever makes sense for the team.”

Brown and Tatum both turned in productive nights, as well, with the former tallying 18 points (7-for-12), eight rebounds and four assists and the latter going for 16-10-6 in 23 minutes apiece. Tatum was 5-for-11 from the field and 3-for-8 from 3-point range.

Holiday, the only Celtics starter who did not play after halftime, went an efficient 4-for-5 from the floor (nine points). The rest were shut down midway through the third quarter.

Given their workloads in this one, it would not be surprising to see Boston’s entire top unit get the night off when the Toronto Raptors come to Causeway Street on Sunday night (7 p.m. ET).

Bench report

Xavier Tillman was Boston’s first sub, checking in for Kornet six minutes in, and he kept up positive momentum from beyond the arc. A career 26.7% 3-point shooter, the 6-foot-8 big man made all three of his triples Saturday night and is 6-for-8 from deep this preseason (80%).

Sam Hauser, whom teammate Payton Pritchard this week called one of the NBA’s best shooters, went 5-for-6 from three in the lopsided win.

Mazzulla shook up his second unit, swapping out Jaden Springer and Jordan Walsh for Lonnie Walker IV and Baylor Scheierman. Walker and Scheierman both did not play until the fourth quarter in either of the team’s first two exhibitions.

Walker finished with nine points (4-for-7; 1-for-4), seven assists and four boards in 24 minutes — an improvement over his back-to-back scoreless cameos in Abu Dhabi. Scheierman, Boston’s first-round draft pick, made three buckets in his TD Garden debut: a pair of corner threes and a layup off a JD Davison feed.

Walsh played the entire fourth quarter and continued his promising preseason, going 3-for-3 from three to finish with 11 points. Springer was one of four Celtics who dressed but did not play, along with Drew Peterson, Ron Harper Jr. and Anton Watson.

Return of Yabu

Among the reserves starting for Philly was a familiar name to Celtics fans: Guerschon Yabusele

Yabusele, a 2016 Boston draft pick who spent the last five seasons playing in Europe, earned another NBA shot after starring for his native France at the Summer Olympics. He averaged 19.6 points per game in the knockout rounds to help lead the host nation to a surprise silver medal.

Three weeks after the Olympics ended, Yabusele signed with the Sixers. On Saturday, the burly 28-year-old started at center against his former team.

“We’re really in the early stages with him,” Sixers head coach Nick Nurse said pregame. “We’re trying to figure out exactly where we’re going to need him the most, and some of that is going to depend positionally what we’re talking about. … He’s been good. He’s been a nice surprise so far, but we’ve got to (learn) some more info.”

Yabusele appeared in 74 games over his two seasons with Boston, averaging 2.3 points and 1.4 rebounds per game. He has not played a regular-season NBA minute since 2019.

“(Returning to Boston is) a special feeling for sure,” Yabusele told reporters before tipoff. “Especially (Friday) when it was driving around the city, just being able to come back, it was really a special feeling. And coming out here to the arena, see a couple of the changes, but can’t wait for the environment for tonight to be able to be with the fans and just enjoy the moment.”

Yabusele said he heard from multiple teams post-Olympics but received the strongest interest from the Sixers, who’d spoken with his agent multiple times during his stint with Spanish club Real Madrid.

“It’s been five years and, of course, when the summer was coming, I was expecting to get a call, but it just made me work harder, keep pushing, never giving up,” Yabusele said. “And every time I was going back on my team I was like, ‘I’ve gotta do more.’ So it was just a long process but I think it was much needed. I’m a different player now, and I understand things more and I just keep on pushing.”

Off the rim

Boston will need to wait another 2 1/2 months to see Philly’s new big three of Joel Embiid, Tyrese Maxey and offseason pickup Paul George in action. The Atlantic Division rivals’ first regular-season meeting isn’t until Christmas Day. … TD Garden pulled double duty Saturday, hosting home games for both the Celtics and Bruins. The B’s beat the Los Angeles Kings 2-1 in overtime in a 1 p.m. matinee. The Garden roommates will play at home on the same day just twice during the NBA regular season: Nov. 16, when the Bruins host the Blues and the Celtics host the Raptors, and Dec. 12 (Flyers and Grizzlies).