Chiefs quarterback Matt Cassel has a strained medial collateral ligament in his left knee and could miss the Chiefs' season opener and beyond, Yahoo Sports! reported on Monday.
Citing a source within the organization, Yahoo Sports! reported Cassel could miss two to four weeks. He was hurt Saturday night when sacked on the third play of a 14-10 preseason loss to Seattle.
The Chiefs open the regular season Sept. 13 at Baltimore. They return to practice Monday and are expected to have injury updates on Cassel and others, including wide receiver Devard Darling (leg).
Tyler Thigpen is Cassel's primary backup.