Dallas scored four unanswered goals after falling behind early.
The win was especially sweet for the Burn since Rapids defender Rick Titus struggled while being directly involved in three of Dallas' four goals. Before the playoffs started, Titus was quoted as saying, "Dallas is done. They peaked too early in the season."
Colorado got on the scoreboard before the full roster announcements were made on a Carlos Valderrama header in the second minute.
Midfielder Chris Henderson played a throw-in to forward Chris Carrieri on the left flank. Carrieri, who came from behind the Burn defense turned on the ball and sent a right-footed cross to Valderrama. He outjumped Burn defender Antonio Martinez and nodded the ball past a stunned Burn goalkeeper Matt Jordan.
Dallas defender Steve Morrow continued his mastery of Colorado when he knotted the score in the 26th minute off a "Chivas" Martinez corner kick. The former Northern Ireland international beat out Titus in the air to flick a header past the far left post and Rapids 'keeper David Kramer. Morrow's goal was the fourth of the year for him, all coming against the Rapids.
The Burn came out in the second half nearly as quick as the Rapids did in the start of the game. Jason Kreis scored just the fourth playoff goal of his career in the 49th minute when midfielder Ronnie O'Brien beat Rapids defenders Robin Fraser and Titus with a cross from the right wing that found a wide-open Kreis, who had the entire net to work with, in front of the net for the go-ahead goal.
Burn midfielder Chad Deering put an insurance goal on the board in the 68th minute. Forward Eddie Johnson, entering the game moments earlier, held the ball at the endline and found Deering at the top of the penalty area, from where he one-timed a shot.
His right-footed blast deflected off Titus and past Kramer.
Martinez scored the Burn's fourth goal of the match in the 70th minute. "Chivas" played a give-and-go with midfielder Oscar Pareja before placing the ball through the legs of Kramer for the insurmountable lead.
The series continues Saturday night in Denver, where the Burn will try to sweep and move onto the semifinal round.