The Portland Timbers punched their ticket to Major League Soccer's Western Conference final with a 1-0 win over the Colorado Rapids on Thursday that also extended their winning streak to six games.

Larrys Mabiala scored in the 90th minute during a mad scramble in front of the Rapids' goal as the Timbers advanced to the conference final for the first time since winning the MLS Cup in 2015.

The scoring play started with a corner kick. Then Felipe Mora's shot from in close was blocked and the ball ricochetted off a defender to Mabiala, who lifted a right-footed shot from the centre of the box over Rapid goalkeeper William Yarbrough.

Portland will face either Sporting Kansas City or Real Salt Lake next weekend.

The Timbers had to play the final three minutes with 10 players after Darion Asprilla was handed a red card penalty. Asprilla will also be suspended for the conference final game.

Portland outshot Colorado 12-10 overall despite being outshot 9-2 in the first half. Portland goalkeeper Steve Clark made all three of his saves in the first half.

The Rapids went 17-7-10 in the regular season and their 61 points were one ahead of the Seattle Sounders.