Graham Zusi assisted on each of the goals for Sporting KC, which beat Colorado, 2-0, Sunday to open the two-game, aggregate-goal playoff. Sporting KC will play the Houston Dynamo or Philadelphia Union in the conference finals Sunday at Livestrong Sporting Park.

Houston won its first leg against Philadelphia, 2-1. They play again tonight.

Collin scored in the 28th minute when he deflected Zusi’s free kick, and Sapong returned from a scary collision in front of the net early in the second half to direct a perfect header past Colorado goalkeeper Matt Pickens in the 76th minute.

Sapong took off running for the corner in glee, sliding through the wet turf before the rest of his teammate piled on in joy. Sporting KC is back in the Eastern Conference finals for the first time since 1997.

Sounders FC 2, Real Salt Lake 0 - Osvaldo Alonso and Lamar Neagle scored five minutes apart early in the second half for Seattle, but Real Salt Lake advanced to the Western Conference final with a 3-2 aggregate win at Seattle.

The loss ended the career of Seattle goalkeeper Kasey Keller, who previously announced he would retire after the season.

Trailing, 3-0 (aggregate), and with just 45 minutes remaining in their season, the Sounders turned the final 30 minutes into a frantic mess, and that came after a breakneck first half in which Seattle nearly scored on numerous occasions.