(Reuters) - Kansas City Chiefs running back Jamaal Charles suffered a torn right anterior cruciate ligament in the team's 18-17 loss to the Chicago Bears on Sunday.
Kansas City coach Andy Reid revealed after the game that the preliminary diagnosis was that four-times Pro Bowler Charles had a torn ACL, and would undergo a MRI and further tests on Monday to determine the extent of the knee injury.
Charles left the game in the third quarter after his right knee appeared to buckle as he was cutting left on a run up on the middle.
He was not hit on the play, but grabbed his leg and was helped off the field with the Chiefs leading 17-3.
Charles missed most of the 2011 season with a torn ACL in his left knee.
The Chiefs fell to 1-4 with their loss to the Bears.
Reporting by Tim Wharnsby in Toronto; Editing by Andrew Both