Celtics were determined not to be dominated on their home floor again by the Raptors

The Celtics’ Marcus Smart is corralled as he heads to the basket by the Raptors' Malachi Flynn, who was called for a flagrant 1 foul.Jim Davis/Globe Staff

The Celtics held a 16-point halftime lead against the Raptors on Wednesday night, and in most situations that would be rather comforting. But the memories of Toronto’s visit to Boston less than one month ago probably remained vivid.

In that game, the Raptors trailed at halftime before throttling the Celtics by 28 points after the break, an early nadir of this up-and-down season. This time, however, Boston did not wilt. It never surrendered the lead and eventually secured a relatively comfortable 104-88 win, its first at TD Garden this season.

During the fourth quarter of the Raptors’ win here last month, the Celtics were serenaded with boos. On Wednesday night, fans happily did the wave and saluted the starters when they went to the bench in the final minute, when the outcome was decided. The angst level has subsided, at least for now.

“We were hurt by what we did in the first game against these guys,” Celtics coach Ime Udoka said, “and really took it to heart and brought the effort tonight.”

Jayson Tatum had 22 points, 12 rebounds, and 7 assists to lead Boston, although he made just 8 of 24 shots and is mired in a bit of an early-season slump. That is partly due to the attention he is drawing from defenses, of course. And the absence of Jaylen Brown, who is out because of a hamstring strain, allows opponents to swarm Tatum even more aggressively. But he is working to make an impact in other ways, as his rebound and assist numbers indicate.

Robert Williams added 16 points and 13 rebounds for Boston and mostly controlled the interior.

Robert Williams and Jayson Tatum celebrate during the fourth quarter of Wednesday's win.Jim Davis/Globe Staff

“It was all aggressiveness,” Williams said. “And to be honest, I felt like us as a team, not just me, did a great job rebounding. We did a great job with physicality. We knew we were lacking that, so we did a great job stepping that up.”

The Celtics forced 18 turnovers and surrendered just six offensive rebounds. In the October game, Toronto gobbled up 21 of them. Udoka said that Celtics coaches emphasized the importance of rebounding so much over the past few days that the players probably got sick of hearing about it. But it seems that it resonated.

Raptors star Pascal Siakam is back after missing the season’s first 10 games because of a shoulder injury. While Toronto is happy to have Siakam, his return altered the Raptors lineup a bit, as he replaced rim-protecting and rebound-gobbling big man Precious Achiuwa in the starting five.

The Celtics were aware of this, of course, and they were confident that the personnel shifts would allow them to be more of a presence in the paint, where they were mostly battered in the October game.

Toronto's OG Anunoby plays some high-flying defense against Josh Richardson in the second quarter Wednesday night at TD Garden.Jim Davis/Globe Staff

“We really told our bigs to really attack the glass, make them pay,” Udoka said. “That’s the first part of keeping them out of transition. Make them focus on boxing us out on the defensive glass and it can slow down transition, as well.”

Early-season results are always magnified, but it seems the Celtics have steadied themselves after their frustrating start. They have won three of their last four games, the only loss coming after Mavericks superstar Luka Doncic drilled a buzzer-beating 3-pointer in Dallas last Saturday.

It’s clear that the resurgence has been sparked by defense, and it’s even clearer that this will be Boston’s most sustainable path to success this season. The Celtics held the Magic and Heat below 80 points last week, and they surrendered just 88 to the Raptors.

“We’ve been playing very well [on defense],” Celtics guard Marcus Smart said. “We have a lot of weapons on that end to be able to do it. So, it was a lot of new guys getting used to everybody. New defense, it didn’t start off well for us, but we’re picking things up and guys are coming along. The chemistry on that end is coming along.”

With the game well in hand late in the fourth quarter Wednesday night, Ime Udoka pulled most of his regulars, and he had a smile for Jayson Tatum as he walked by him on the way to the bench.Jim Davis/Globe Staff/file

The Celtics led by as many as 18 points in the second quarter, but the Raptors pulled within 87-79 on an OG Anunoby layup with 7:01 left. The Celtics, who never trailed, responded with an 8-0 run that was capped with consecutive steals and layups, stretching the lead to 95-79.

Udoka said he was pleased with how the Celtics punched back after the Raptors made their mild run. Smart said Boston’s demeanor was noticeably different this time.

“Got tired of getting our [butts] kicked, you know?” Smart said. “It shows. We continue to go out there and play 48 minutes, too, and that was the difference. They came in last time and they ran us off the floor, and we made sure that didn’t happen again tonight.”