DENVER (Ticker) -- Ben Olsen scored the game's lone goal in the 16th minute as D.C. United became the first MLS team to clinch a playoff berth this season with a 1-0 victory over the Colorado Rapids in a game between conference leaders.

Olsen gave United the early lead when forward Jaime Moreno played a ball back from the penalty box to Geoff Aunger, whose looping ball found Olsen beating Ross Paule and the Rapids' offside trap. He slammed the ball past Colorado goalkeeper Ian Feuer for his fifth goal.

Despite being outshot 19-9 overall and 7-3 in shots on goal, United (19-7, 47 points) improved to 11-3 on the road this season and ensured they will finish no lower than second place in the Eastern Conference.

The three-time Eastern Conference champs and two-time MLS Cup winners lead the Columbus Crew by 12 points and will finish ahead of Tampa Bay, Miami and New England, which are competing for the two remaining playoff spots.

Late-game heroics were almost in store once again for Colorado forward Jorge Dely Valdes, whose headed goal in the 86th minute was waved off following a foul in the box by Marcelo Balboa.

Balboa saw numerous opportunities to knot the game for the Rapids, coming close to tying the game with a 23-yard blast that went just wide in the 88th minute. Balboa, whose free kick with 10 minutes remaining was juggled by D.C. United goalkeeper Mark Simpson, also missed a volley with 22 seconds on the clock, sending his offering high over the empty net.

Colorado (16-8, 42 points) fell to 4-4 in its last eight games after opening the season 12-4 and building its Western Conference lead, which has now dwindled to two points after Chicago's regulation win at home and Dallas' 1-0 win against Los Angeles.

The Rapids have lost three of their last four games and atop a four-team logjam separated by four points in the Western Conference.