Marco Pappa has been one of the biggest catalysts for the Colorado Rapids’ surprising start to the season since he was dealt from the Seattle Sounders in December, but he won’t get the chance to play against his former club this weekend.

The Rapids announced Monday that Pappa is out two to four weeks with an MCL sprain in his left knee, meaning he’ll miss the Rapids’ game against the Sounders at Dick’s Sporting Goods Park on Saturday (6 p.m. PT; Q13 FOX/KIRO 97.3 FM/EL Rey 1360AM).

Pappa, 28, suffered the injury in a knee-on-knee collision with New York Red Bulls' defender Kemar Lawrence in the 71st minute of Colorado's 2-1 win Saturday.

The Rapids said Pappa's injury was confirmed by an MRI Monday morning. The club said the injury was "non-surgical" and Pappa will begin rehab immediately.

Pappa leads the Rapids with three assists in seven appearances this season, and he scored a goal in the team’s 1-0 upset over the LA Galaxy on March 12.

The Rapids have won two straight games and three of their last four heading into the weekend.

The Sounders dealt Pappa to the Rapids late last year in exchange for an undisclosed amount of allocation money. Pappa scored nine goals over 49 regular-season appearances and added two assists in six postseason games.