Kansas City quarterback Matt Cassel has a sprained 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.
Head coach Todd Haley refused to comment Monday on the status of Cassel.
"I'm only going to talk about the players who are on the field," Haley said.