FOXBOROUGH, Mass. (AP) $ New England Patriots quarterback Tom Brady, the NFL's reigning MVP and one of the most consistent starters in league history, was scheduled for an MRI on Monday amid reports that he sustained a season-ending injury to his left knee.

Brady, whose streak of 128 straight starts is the third-longest ever, left Sunday's game against Kansas City after he was hit by Chiefs safety Bernard Pollard in the first quarter of New England's 17-10 victory. Patriots coach Bill Belichick offered no information on the injury, and Brady was not available for comment after the game, but reports circulated around the league that he had torn his anterior cruciate ligament.

"That's terrible. Terrible. I guess it's an ACL or something," Jets quarterback Brett Favre said Sunday. "They've always overcome injuries and things like that, but that's pretty difficult, Tom Brady."

Backup Matt Cassel said Monday he was ready to fill in for Brady next week against the New York Jets $ and longer, if necessary.

"I'm not trying to be Tom Brady. I'm just trying to be Matt Cassel," he said when subbing for Brady on his regular weekly radio show. "I don't know where that's going to take us."

Cassel could have some competition: A person familiar with the situation told The Associated Press that former Tampa Bay quarterback Chris Simms was heading to Foxborough on Monday for a physical, and reports elsewhere said Tim Rattay was also being considered.

Cassel said on WEEI-AM that he hadn't talked to Brady, though the two had exchanged text messages. Cassel wasn't asked about Brady's injury.