Cassel, who signed a six-year contract for a guaranteed $28 million, injured his knee on the third play of the third preseason game against Seattle. He was in full uniform Monday and did most of the conditioning drills in the short period the media were permitted to watch. If he does not start at Baltimore, the Chiefs would probably go with Brodie Croyle.
Coach Todd Haley was evasive whether Cassel would play Sunday.
"I think that as the week goes on, we'll know a little bit more," said Haley. "We'll know a little bit more with Matt for sure. But it was good that he was out there. He was able to get through some things. As the week goes on a little further, we'll know a little more as far as where he's at."
Cassel's backups, Croyle and Tyler Thigpen, were both inconsistent as the Chiefs went 0-4 in Haley's first preseason as their coach. Cassel, who stepped in for an injured Tom Brady with New England last year and won 11 games, hit 11 of 19 passes for 114 yards and one TD.
Croyle saw the most action and was 22 of 44 for 271 yards. The offense scored only two touchdowns in four preseason games.
"It's good this is a long week. That will help with anybody who's nicked up," said Haley. "I would say generally you would need to have a full practice to have a chance to play. Generally, you need to have a full Friday practice to have a chance."