BOSTON — Even on a day when the Nets won a game, they lost.

Point guard Jarrett Jack went down with a knee injury in the third quarter and did not return Saturday, turning the Nets’ 100-97 victory over the Celtics at TD Garden into a Pyrrhic one.

Jack was driving to the hoop on a breakaway when his right knee buckled. He hit the floor hard, was slow to get up and eventually was helped off the court by two others. He didn’t put any weight on his right leg at the time but was walking — with a limp — in the locker room after the game.

The Nets, who scheduled an MRI for Sunday, called it a right knee strain. “I’ve never felt pain like that before, so I knew it was something,” Jack said. “I’m playing the waiting game, just like everybody else.”

Jack was forced to sit as the Nets (10-23) nearly blew an eight-point cushion in the final minute. The Nets built a 98-90 lead, but Boston (18-15) had the ball with a chance to tie it at the buzzer.

Thaddeus Young’s inbounds pass with 11.1 seconds to go found Celtics guard Marcus Smart, who got the ball to a wide-open Jonas Jerebko. The ensuing corner three-point try bounced off the rim, the last of 25 Boston misses from beyond the arc (the Celtics made seven in the game). Boston couldn’t get another shot off.

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With the Nets losing eight of their previous 10 games, coach Lionel Hollins was happy to get out with a win, acknowledging that his players didn’t execute well down the stretch.

“But we won the game, so it doesn’t really matter,” Hollins said. “We were fortunate. I chalk it up to we were fortunate.”

Brook Lopez led the Nets with 30 points and 13 rebounds, his third straight 20-10 game. Joe Johnson had 20 points and Young added 16 points and 10 rebounds.

A 9-0 Nets run followed an early second-half skirmish. Boston’s Jared Sullinger flagrantly fouled Lopez and Jack came to Lopez’s defense. Jack had to be separated from Jae Crowder and several other Celtics.

“I just felt that the play he made really wasn’t a basketball one,” Jack said. “People can get hurt, especially when you do things up around the neck area with force. We can’t tolerate stuff like that.”

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