Four minutes into the second quarter of the Celtics’ game against the Rockets on Monday, Kristaps Porzingis missed inside, grabbed his own rebound, and threw down a loud dunk. Then he stomped toward his defender, Dillon Brooks, and gave him a bump, resulting in a technical foul.
Brooks is known as one of the game’s biggest pests, and he is very good at playing defense. In this case, Porzingis seemed to relish getting the better of him while taking his own rare turn as an agitator. Brooks is not known as an offensive weapon, but on this night he responded loudly and forcefully at the other end of the floor.
The guard smashed his career high and tied the Rockets’ franchise record by drilling 10 of 15 3-pointers, and Houston stunned the Celtics, 114-112, when Amen Thompson hit a shot in the lane with 0.7 seconds left.
Brooks scored 36 points and Thompson finished with a career-high 33 for Houston, which overcame a pair of double-digit deficits, including a 12-point hole with less than nine minutes left.
Thompson’s point total frustrated the Celtics, but Brooks’s explosion left them shaking their heads.
When Jayson Tatum was asked about how Boston battled until the end in its first game after a lengthy Western Conference road trip, Brooks was on his mind more than any moral victory. He read Brooks’s stat line and pointed out that it was a record.
“We didn’t expect that, for sure,” Tatum said.
Brooks said Porzingis’s antics supplied no extra motivation. He was already 4 for 4 from beyond the arc, and said he was more focused on simply winning at TD Garden for the first time in his career. Then he slid in a quick dig with a wry smile.
“I like playing against bigs,” he said. “They’re slow.”
The Celtics were positioned to overcome Brooks’s eruption, but ultimately doomed by shoddy defensive execution on Houston’s final two possessions.
After two Jaylen Brown free throws tied the score at 110, with 11.8 seconds left, Alperen Sengun shook Celtics center Luke Kornet with a backdoor cut and slid to the rim for an easy dunk.
“I put myself in a bad position on that play,” Kornet said. “I should’ve just fouled him or just taken him out. I don’t know. For whatever reason, I kind of got off to the side of him and then he cut and yeah, I was behind him.”
Tatum, who was held scoreless in the first half, attacked for a layup with 5.3 seconds left to tie the score again.
During the ensuing timeout, Rockets coach Ime Udoka designed a play for Thompson, who typically is not one of Houston’s three main scoring options.
“Nobody really said anything,” Thompson said. “[Udoka] just drew up the play and I was like, ‘Oh, [expletive], I’ll take this.’
Before the ball was inbounded, Brown looked to switch onto Thompson near the free throw line. But there was miscommunication with Kornet, causing both players to hesitate. That left Brown just off-balance enough for Thompson to get a step on him and find space for a runner in the lane with 0.7 seconds left.
“I guess I should’ve sniffed it out earlier,” Brown said. “But we tried to communicate the switch to get Luke off of Thompson because he had it going, and they were going to go to him, and the timing was [off].”
After the game, Celtics coach Joe Mazzulla took responsibility for the late defensive lapses.
“Those last two plays were on me,” he said. “Those were my fault. It didn’t put us in the best matchups. I saw the play that they were trying to run. I tried to change the matchups. They put our guys in a tough spot. So that’s a tough one, because I thought our guys did everything to win the game, and they put us in position to win it, and I didn’t help them at the end. So both those plays, 100 percent on me.”
The Celtics still had 0.7 seconds left after Thompson’s basket, but they were out of timeouts because they lost a challenge of a Jrue Holiday foul a few minutes earlier. So they were unable to advance the ball, and Payton Pritchard’s heave at the buzzer never really had a chance.
Brown had 28 points and Tatum, who played the entire second half, finished with 19. Derrick White (shin) and Sam Hauser (hip) were ruled out about an hour before tipoff. Al Horford (toe) was activated after being listed as questionable with a toe injury but pulled from the starting lineup at the last minute, and he did not play.
“Right before the game, he just didn’t feel comfortable going,” Mazzulla said. “But he did everything he could to play.”
The Celtics (32-15) dropped to 8-6 in January and 15-9 at TD Garden this season. They have a one-game lead over the Knicks for second place in the East.
Adam Himmelsbach can be reached at adam.himmelsbach@globe.com. Follow him @adamhimmelsbach.