Yao scored only seven points on 2-for-7 shooting, but Shane Battier scored 16 points as Houston beat the Blazers for the 11th time in the last 12 meetings at the Toyota Center. Game 4 is Sunday in Houston.
Battier and Ron Artest blanketed Roy most of the night, bumping him every time he touched the ball. Artest only scored nine points and Houston still led most of the way.
"We play as a team," Scola said. "So because of that, we can afford for Ron and Yao to have a bad night and we still win. And that's a good thing to have."
Roy, who scored 42 points in Portland's 107-103 win in Game 2, had 19 points, but went 6-for-18 from the field. Even when he broke free from Battier or Artest, Houston's defense seemed to converge on him in the lane.
"They were collapsing everybody," said Roy, the NBA's No. 10 scorer. "They [Artest and Battier] did a good job of trying to stay with me. It didn't matter where the screens came from, they tried to stay with me. But the other guys did a good job of clogging the paint."
Steve Blake scored 16 and had 10 assists, and Rudy Fernandez sank five 3-pointers and finished with 17 points for the Blazers, who trailed by 17 in the second half before rallying in the final quarter.
LaMarcus Aldridge's 3-pointer with 24 seconds left cut Houston's lead to 80-77. Aaron Brooks hit a free throw before Fernandez swished a 3-pointer from the corner. Brooks hit two more free throws with 16 seconds left, Blake badly missed a 3-point try and the Rockets sealed it from the free-throw line in the closing seconds.
After shooting 51 percent in Game 2, the Blazers shot 42 percent on Friday.
"We didn't get into a rhythm all night long," Portland coach Nate McMillan said.
The Blazers tried to be physical, too, especially on Yao. Joel Przybilla earned a technical foul in the first quarter for delivering an extra shove on Yao.
Much of the talk leading into Game 3 focused on Portland's double-teams on Yao and the Blazers successfully stifled him with that strategy again.
"Tough for me," Yao said. "Almost like a sandwich. I cannot let that defense beat me."
Houston coach Rick Adelman said Yao needs to create more space for himself to get the ball. If he doesn't, Adelman said the Rockets will find other ways to score.
"He's just got to understand how they're playing him and be patient enough," Adelman said. "If they want to take that away and we win the game, so be it."
Most of Portland's problems came at the other end -- the Blazers started 4-for-16 from the field.
Yao was out early in the second quarter and Scola hit a jumper and converted a three-point play. The Rockets hit six straight shots, including a breakaway dunk by Von Wafer, to stretch the lead to 34-22.
Houston went 12-for-15 from the field in the quarter to lead 48-37 at the break. Roy was 2-for-7 from the field and Aldridge, who scored 27 points in Game 2, was 2-for-8.
Aldridge was called for an offensive foul in the first minute of the second half and Yao flipped an assist to Battier for an easy layup.
Scola earned his fourth foul and went to the bench with 6:57 left in the third quarter and Aldridge's turnaround over Carl Landry cut Houston's lead to 54-44. Portland got two dunks from Greg Oden and another from Aldridge on consecutive possessions to launch the second-half rally.
The Blazers rallied from double-digit deficits to win an NBA-best 18 games this season, but couldn't quite finish this one.
Landry scored 10 off the bench. The Rockets' reserves scored 24 points in all, on 10-for-18 shooting. ... Portland dropped to 9-2 in games decided by three points or fewer. ... Houston G Tracy McGrady, who underwent season-ending microfracture surgery on his left knee on Feb. 24, sat on the Rockets' bench. Referee Dick Bavetta jokingly bounced the ball to him just before the opening tipoff. McGrady squeezed the ball and gave Bavetta a wry smile before bouncing it back.