Mabiala scored for the second straight playoff game in a scrum following a corner kick.
Felipe lives saw his right foot shot at close range blocked, but the ball slipped through a defender in Mabiala. Mabiala blocked the ball and landed a right-footed shot from the center of the box just above the Colorado goalkeeper William yarbrough.
The fourth-seeded Timbers have advanced to the conference final for the first time since winning the 2015 MLS Cup. Portland will face Kansas City Sports Where Real salt lake next weekend and will get the home game if RSL advances.
Mabiala marked a day when Sebastien Blanc came out early in the second half with an apparent leg injury. Four minutes after Mabiala’s clutch countdown, Portland’s Darion Asprilla received a red card giving him an automatic suspension for the next round and forcing the Timbers to play the final three minutes with 10 players.
Portland goalkeeper Steve clark made his three saves in the first half. Portland was outscored 9-2 in the first half but ended up with a 12-10 shooting advantage.
In the 14th minute, Clark made a diving save on Dominique Badjii. He made another dive stop when he stopped Cole bassettleft foot attempt in the 28th minute.
Colorado were unable to advance on a day when they held the ball 55.1 percent of the game. The setback was his second at home this season.
Yarbrough made three saves but was slightly out of position when Portland scored.
Before Portland scored the game-winning goal, he had four 65th-minute chances diverted by the Colorado defense.
Jaroslaw Niezgoda started it when its header was blocked before Claudio Bravo had a long blocked shot. Yimmi charathe shot from the right foot moved to the left and Josecarlos Van Rankin’s attempt from a sharp angle was blocked.
Portland missed another chance in the 84th minute when he got a quick break to see Chara’s left-footed shot from six yards away sailed well to the left. Chara missed another chance four minutes later when Yarbrough used his right hand to repel the shot.