The Houston Rockets downed the Portland Trail Blazers to move within one win of the Western Conference semi-finals.

Yao Ming scored 21 points and dished out 12 rebounds at the Toyota Cente.

Luis Scola scored 17 points and Shane Battier added 14 and six assists as Houston moved 3-1 ahead in the quarter-final series ahead of Game Five in Portland on Tuesday.

Brandon Roy scored 31 points and went 13-for-13 from the free-throw line for the Trail Blazers, while LaMarcus Aldridge chipped in with 19 points and 10 rebounds.

After trailing 50-44 at the break, Portland led 70-64 at the end of the third quarter but the Rockets responded and led 87-85 with 27 seconds remaining.

Aaron Brooks could only make 1-of-2 free throws with 10 seconds to play, but after Travis Outlaw missed a 3-pointer for Portland, Brooks sank another free throw and Rudy Fernandez converted from the arc with just over two seconds remaining to secure the win as the Trail Blazers failed to create a shooting opportunity.