HOUSTON — Celtics head coach Doc Rivers chatted with Rockets general manager Daryl Morey after Boston's 103-99 victory over Houston on Tuesday night.

"Y'all are going to be great," Rivers said. "I'm telling you."

Maybe so. But the defending NBA champions showed the Rockets how far they still have to go.

Ray Allen scored 29 points, Kevin Garnett added 14 points and 11 rebounds and the Celtics shut down Ron Artest and Yao Ming to hand Houston its first loss of the season.

Tracy McGrady scored 26 points, but couldn't rally the Rockets down the stretch.

The Celtics arrived in Houston thinking more about their 95-79 loss to Indiana on Saturday than the buzz they've heard about the Rockets.

"With Artest coming here, I know they see what we did the previous summer in having three guys who really can play and really can score," said Allen, who hit 11 of 15 shots. "You have a tendency to get caught in the hype of the wrong team and you start to believe it. What we did, we came out here, we lost the last game, and we needed to come out here and do the things we do that make us successful."

The Celtics led 101-97 when McGrady rose for a 3-pointer and was fouled by Tony Allen. McGrady landed awkwardly and grabbed his sore left knee as Rivers protested the call, claiming McGrady was trying to pass. He was given three foul shots and made two, cutting Boston's lead to 101-99.

Eddie House hit two free throws at the other end with 9.6 seconds remaining. Brent Barry then missed and Garnett caught it to secure the win.

"We did not play well at all," said Artest, who missed 13 of 16 shots and scored 15 points by sinking six free throws. "Usually you can say you've got to give them credit. But there were things that we could've done better to pull out the victory."

Paul Pierce added 13 points and nine rebounds for the Celtics. Yao went 4-for-14 from the field and scored eight points for Houston.

"Probably one of my worst games of all time," Yao said.

Houston's reserves helped keep the Rockets in the game. They trailed 81-78 after three quarters.

Yao, Artest and McGrady went a combined 0-for-8 to start the fourth quarter and the Celtics led 93-86 with 31/2 minutes left. McGrady converted a three-point play, but Ray Allen hit a 3-pointer at the other end. McGrady then hit a shorter shot and Ray Allen answered again.

The Celtics ended the Rockets' 22-game winning streak last season with a 94-74 win at the Toyota Center on March 18.