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Yao Ming had 27 points and seven rebounds.
HOUSTON, March 22 (AP) -- The Houston Rockets built a big lead on Detroit on Thursday, playing at the level coach Jeff Van Gundy wants to see when the postseason begins.
Then came the fourth quarter.
Yao Ming scored 27 points, grabbed seven rebounds and made a key block in the final minute as the Rockets hung on for a 91-85 victory over the Pistons.
"We all played great for three quarters,'' said Yao. "We didn't play well in the fourth, but that's a good lesson for us and we're going to learn for the playoffs.''
The Rockets have won eight of 10 games since Yao returned from a broken leg, but Van Gundy says it's Yao who needs to pick up his play late in games if the Rockets are hoping to make a deep playoff run.
"He needs to be a killer if we're going to do anything,'' Van Gundy said. "We've got to be able to go to him late. He's got to be able to get good, clean looks. He needs to develop a finishing mentality.''
Tracy McGrady added 20 points and eight assists and Rafer Alston went 3-for-5 from 3-point range and scored 16 for the Rockets, who've won five in a row and eight of their past nine games. Houston trails Utah by a half game in the race for the fourth-best record in the West.
"Whenever you beat a championship-caliber team like them, it says a lot about your ballclub,'' said Alston.
Antonio McDyess scored 16 and Chauncey Billups added 13 points and six assists for Detroit, which had its six-game road winning streak snapped. Billups was back in the lineup after missing two games with a strained groin.
At one point, Billups shed a wrap on the injury and played better without it.
"It was tight early and then it started loosening up after the half and then I attacked the basket,'' said Billups, who scored 11 points in the second half.
The Rockets shot well at the start and again early in the third quarter to build double-digit leads.
Billups converted a three-point play, then swished a 3-pointer to cap Detroit's rally and trim Houston's lead to 86-82.
Alston scored and McGrady hit a jumper from the corner to put Houston up 90-83, but McDyess answered with a free throw. After McGrady lost the ball, Detroit got it to Carlos Delfino, who drove the lane but had his shot blocked by Yao with 22 seconds left.
"We played catch-up all game,'' McDyess said, "and eventually, you run out of gas when you are in an uphill battle.''
Alston hit a free throw with 17.3 seconds left for the final margin.
"I was happy Yao got that last block,'' Alston said with a relieved smile.
The Rockets opened the game with a 16-2 run, even though Yao picked up two fouls in the first 90 seconds. McGrady drove past Tayshaun Prince for a one-handed dunk, then beat him again on an acrobatic layup and Shane Battier hit a 3-pointer from the corner during the spurt.
Detroit missed its first seven shots before Richard Hamilton raced for a fast-break layup. The Pistons started 2-for-14, then found their range and trailed 20-15 after the first quarter.
The Rockets went 11-for-14 from the free-throw line in the second quarter to maintain their lead.
McGrady sank two long jumpers and found Chuck Hayes for a layup late in the half to start an 18-6 run that bridged the second and third quarters.
"I was very happy with the first three quarters,'' Van Gundy said. "We defended well early, we got quality shots on through the half and the start of the second half.''
The Rockets hit 6 of their first 7 shots out of halftime and led 60-41 after Yao flipped in a turnaround jumper with 9:23 left in the third quarter.
The flustered Pistons trailed 66-47 when Billups received a technical foul for complaining about an offensive foul on Hamilton. Yao sank the free throw to give Houston its first 20-point lead.
McGrady scored Houston's last six points of the quarter and the Rockets led 73-56 heading to the fourth.
But the Rockets nearly collapsed and hung on to snap a six-game losing streak to Detroit.
Van Gundy said his team has a month to learn how to put teams away. Otherwise, he fears a first-round exit from the playoffs.
"We don't have a finishing mentality,'' Van Gundy said. "That lack of a finishing mentality, if we can't correct it within the next 27 days, it will come back to bite us at the most inopportune time.''
Notes: The Pistons lost for only the sixth time in their past 24 games. ... The Rockets are 24-3 when they lead after three quarters. ... The Rockets' five-game winning streak matches a season high.