President of basketball operations Danny Ainge pushed aside the distractions of Glen Davis’s freakish injury and Rajon Rondo’s summer-long contract negotiations and concentrated on those offseason moves that helped the Celtics outlast Cleveland, 95-89, in front of a sellout crowd of 20,562.

And perhaps the biggest offseason development was not a free agent signing but the rehabilitation of Kevin Garnett, who was battered and pounded during his 33 minutes but finished with 13 points, 10 rebounds, and 3 blocks in his first game since March 25.

After seven months of anticipation regarding Garnett’s health, the Celtics got a workmanlike effort from their spiritual leader. His surgically repaired right knee held up to a series of challenges. And when it was apparent Garnett was here to stay, the Celtics took a deep breath and counterpunched the Cavaliers, taking a 15-point third-quarter lead they would never relinquish, despite a furious effort from LeBron James.

The reigning MVP scored 38 points, looking like a one-man team in many stretches, which was the Cavaliers’ major issue in June’s playoff loss to Orlando.

With the hard-charging Cavaliers trailing by 6 with less than three minutes left, Garnett drained a turnaround 13-footer off the glass for an 87-79 lead and strutted down the floor gleaming with confidence.

“I’m telling you man, I don’t have any hesitations when it comes to playing,’’ he said. “Healthwise, I’m very decent and I’m very strong. It’s a process. It’s not a sprint. I’m a lot better at being patient with all this. Sometimes I’m thinking you all are expecting I’m dead or something. I’m far from dead. Believe that.’’

If Shaquille O’Neal’s third-quarter takedown of Garnett didn’t inflict serious bodily damage then Garnett is indeed truly fully healthy.

Garnett experienced very few scares during the exhibition season and coach Doc Rivers made sure to preserve his recovering forward with limited minutes. A benchmark for Garnett’s comeback occurred with 10:26 left in the third quarter when Garnett soared to the basket for a two-handed layup and O’Neal, on help defense, grabbed Garnett (who is 100 pounds lighter) and knocked him to the floor.

It was hardly dirty. It was intense Eastern Conference basketball and O’Neal carried out the “no layup’’ rule. Realizing the significance of the moment and relieved that he wasn’t writhing in pain, Garnett took a few deep breaths, rose, and then pounded his chest with his right fist three times.

“That’s the Diesel,’’ he said. “Any one of you run up against the Diesel, I am sure the same thing will happen to you.’’

While he downplayed that moment, his teammates picked up on his enthusiasm.

“I think he was letting everybody know, ‘I ain’t hurt, I’m still moving,’ ’’ guard Eddie House said. “I think he knows that he’s right and he’s going to continue to build on being as strong as he can be.’’

For the remainder of the game, Garnett was fearless. He exchanged shoves in the paint with Zydrunas Ilgauskas. He set picks and popped off ready for feeds from Rajon Rondo. He even leaped so high on a feed from House that he missed a streaking dunk.

Last night wasn’t vintage Garnett, but he showed enough flash to give his teammates a secure feeling and dissipate doubts about his confidence.

“As this year goes on, I think we will have more tests and more measuring sticks,’’ Garnett said. “I was just a little banged up [last season] and hopefully I can get back to where I want to be.’’

Cleveland punched the Celtics in the mouth to begin matters, running out to a 17-4 lead, forcing Boston to take a step back to regroup and remember the defensive chemistry and execution that had been so apparent the previous two years.

The Celtics slowly took control in the second quarter, creating the expected matchup issues that could perplex opposing coaches all season. Rivers mixed and blended his lineups with precision, going nine deep. Marquis Daniels, for example, played three positions in the first half.

When Daniels played shooting guard, smaller Mo Williams was forced to check him, allowing point guard Ray Allen to post up tiny Daniel Gibson for easy scoring opportunities. All nine Celtics scored in the first half as Rivers put them in comfortable positions. House was not relegated to playing point guard, instead he was allowed to roam and shoot open 3-pointers.

Rasheed Wallace (12 points) stretched the floor and hit two 3-pointers, prevented Anderson Varejao from being too much of a menace, and controlled the paint. With Kendrick Perkins having his hands full - literally - with O’Neal, Wallace’s production was critical.

Garnett played just 14 minutes in the first half, scoring 4 points with three rebounds, yet Boston led by 6.

“I think we all realized that this wouldn’t be a game where we put up numbers,’’ Perkins said. “I talked to KG before the game and I said, ‘I don’t think you are going to see 15 rebounds from me tonight.’ And I think we just spread the wealth. That was the key.’’

Gary Washburn can be reached at gwashburn@globe.com.