D.C. United star Dwayne De Rosario, the 2011 MLS most valuable player, will miss the remainder of the season with a knee injury, a major setback for a club seeking its first playoff berth in five years.

De Rosario suffered a Grade 3 sprain to the medial collateral ligament and will be sidelined for 10 to 12 weeks, the club announced Thursday morning. United (12-10-5) has six weeks remaining in the regular season, with the playoffs set to begin at the end of October.

“DeRo is our captain, a great player and impossible to replace,” Coach Ben Olsen said in a prepared statement. “With that said, we have talented players that will step up in his absence and this injury will not be an excuse to fall short of goals we set for ourselves as a team at the beginning of the season.”

De Rosario, who is tied for second in MLS in assists with 12 and has scored seven goals, was injured while on Canadian national team duty at a World Cup qualifier in Panama on Tuesday.

The MLS roster deadline is Friday, and although United has little roster and salary cap space, General Manager Dave Kasper said before the De Rosario announcement was made that “we’ll see” if any deals can be made.

More later.....