BOSTON (AP) -- Tim Duncan beat Glen "Big Baby" Davis a couple of times in the first quarter, and the disappointment on the rookie's face showed.
"We had to remind him that Duncan is really good. That's going to happen," Celtics coach Doc Rivers said Sunday after Boston beat the San Antonio Spurs 98-90. "You can't get frustrated."
Filling in with Kevin Garnett and Kendrick Perkins injured, Davis had nine points and eight rebounds for Boston. Paul Pierce scored 35 points, Ray Allen had 19, and Rajon Rondo had 12 assists and 11 rebounds Sunday as the Celtics won their third straight game improved to 16-0 against the Western Conference.
Duncan had 22 points, 14 rebounds and six assists, and Manu Ginobili scored 21 for the Spurs, who lost for the first time in five games. San Antonio got within three points with 1:13 left, but Michael Finley's 3-point attempt went in and out.
Twice in the final minute Ginobili was forced to take off-balance, heavily guarded 3-point attempts; neither one was close.
"We have an opportunity and a great shot by Mike that rattles in and out to tie the game down the stretch," Duncan said. "Then two turnovers in a row and they get two offensive rebounds. Just too many mistakes that bit us down the stretch there."
The Celtics improved to 5-2 since Garnett went out with an abdominal strain, and they'd better get used to it: Rivers said after the game that his big man -- the leading All-Star vote-getter -- won't be back before the Feb. 17 exhibition in New Orleans.
"He's out until after the All-Star break, I think including the All-Star Game," Rivers said. "That I haven't talked to him about, but I assume so."
Subs Eddie House, who scored all of his 10 points in the second quarter, and James Posey, who had five of his seven rebounds in the fourth, also came off the bench to pitch in.
"I just have to give credit to the whole bench being ready, turning the game around," Pierce said, also praising Rondo for leading the team in rebounds three times since Garnett went out. "Every time he leads the team in rebounds, we win. So keep crashing the boards, Rondo."
But the key was Davis, who combined with Leon Powe to keep Duncan from taking over the game.
"What we told Glen was, 'He's taller than you. You're heavier than him. You're not going to grow today,' " Rivers said. "But because you have a low center of gravity, get into his legs and try to push him off the block. You can't get frustrated. ... He did that a couple of times."
Rivers said he didn't tell Powe he was starting until the walkthrough.
"We don't sit and hold a vigil or anything," the coach said. "We try not to make a big deal of it, because if we do, [he] will."
With Boston leading 92-87 and under 20 seconds left, Ginobili was hacked while trying a 3, but no foul was called and Rondo came up with his second big rebound of the final minute. Rondo made both free throws after he was fouled, then Finley made a 3-pointer to make it 94-90.
But Tony Allen made a pair of free throws, and Ginobili again couldn't get a clean look at a 3.
San Antonio trailed by as many as 10 points in the fourth quarter, cutting it to 89-87 with 2:01 left on Ginobili's 3-pointer. But the Celtics, who made just 10 of 19 free throws through three quarters, made 11 of 12 down the stretch -- including their last eight -- to hold back the charge.
Pierce scored 14 in the first quarter, and Ginobili had 11. Rondo had five assists and five rebounds in the first. ... Red Sox first baseman Kevin Youkilis was sitting courtside. ... Spurs point guard Tony Parker missed his sixth straight game with a sore left ankle. .. The Celtics hadn't beaten San Antonio in Boston since Jan. 8, 1997, a streak of nine consecutive losses.