Montreal ended the game with eight men, but was outplayed and outscored by a tough Houston side.
Carrying two months' worth of disastrous form into the game, Montreal was desperate to put the regular season in the rearview mirror and focus on its first-ever Major League Soccer playoff game, while Houston was looking to kickstart its campaign for a third consecutive Eastern Conference title.
The Impact had some early looks with direct balls to Marco Di Vaio, but it was Houston which drew first blood, in the 16th minute. Charging through the middle, Will Bruin played a one-two with Ricardo Clark that involved a tricky backheel by the midfielder back into Bruin's path, and he applied the powerful finish from close range to make it 1-0.
The Dynamo made it 2-0 in the 27th minute, thanks to an Oscar Boniek Garcia penalty. Hernan Bernadello was at fault for giving away the spot kick, tracking back to commit a needlessly agressive tackle when he had two teammates goalside in close proximity.
Impact defender Nelson Rivas, making his season debut after a long rehab stint, was lucky not to be sent off in the first half for an elbow in the face of Giles Barnes, but a second yellow for a similar foul on Will Bruin ended his season after just 70 minutes.
Bruin punished Montreal almost immediately. Beating Matteo Ferrari in a footrace, he came inside from the left and sidestepped Jeb Brovsky and Troy Perkins before another powerful finish secured his second goal and sealed the result for Houston.
The game turned ugly late on, as a frustrated Montreal side went into a meltdown. Andres Romero was sent off for a petulant kick at Corey Ashe, and in the ensuing fracas, Di Vaio twice put his hands to the Houston defender's face and attempted to scratch him, earning the veteran his own red card.
Houston will now face the New York Red Bulls in the Eastern Conference semifinal.