[ESPN.com] Kansas City running back Jamaal Charles will likely miss the rest of the 2011 season after an initial diagnosis revealed a torn ACL in his left knee following the Chiefs’ 48-3 loss Sunday, a source familiar with the situation told ESPN NFL Insider Adam Schefter.

The source said Charles will have an MRI on Monday to confirm the diagnosis, but the team believes the Pro Bowl running back will not return this year.

Charles, who rushed for 1,467 yards last season, was lunging toward the first down mark along the Detroit sideline when he was pushed out of bounds by defensive back Chris Houston. He landed at the feet of Detroit’s mascot and immediately began clutching his left leg.

His return was initially announced as questionable, but the injury appeared significant, and he was carted off the field. Charles was declared out for the rest of the game early in the third quarter.