KANSAS CITY, Mo. -- Brodie Croyle kept getting hurt and Tyler Thigpen seemed ill-suited for an NFL offense, so the Kansas City Chiefs traded for Matt Cassel and gave him a guaranteed $28 million contract before the first snap.

Now Cassel is hurt, Croyle is healthy and Thigpen is probably still ill-suited. But either he or Croyle could start against the tough defense of the Baltimore Ravens on Sept. 13 in the season opener.

Cassel injured his knee in Saturday night's preseason loss to Seattle and the Chiefs may be down to Croyle and Thigpen, who between them are 1-18 as NFL starters.

The decision will be up to head coach Todd Haley, who stirred his team's murky waters even further on Monday by firing Chan Gailey as offensive coordinator and assuming the role himself, just 13 days before opening his first season as a head coach.

"It's almost unheard of that you have something like that happen right now," Thigpen said. "We've got to take responsibility."

Haley refused to breathe a word about the status of Cassel or any of his other injured starters.

The players indicated they had no inkling how long Cassel might be gone.

"It's unfortunate for Matt," Croyle said. "Who knows the timetable when he'll be back? If it comes time to go, I'll just have to be ready."

The fourth preseason game, usually little more than a final tryout for players trying to make the roster, could be critical for the Kansas City quarterbacks. Whoever shows well against the Rams on Thursday night could find himself calling plays in Baltimore.

"We've got to have our ducks in a row, no doubt," Haley said. "They're going to kick off in 12 days, or 13 days. We've got to have everything lined up and be ready for anything."

Whoever starts and whoever calls plays is likely to have a tough time until the Chiefs get their offensive line straightened out. In just 19 pass plays in the first three preseason games, Cassel was sacked four times, including the play when he got hurt.

"Until we get on the field and we're winning games and doing the things we need to do detail-wise, it doesn't matter who calls the plays," running back Larry Johnson said. "We've got to go out and execute and do the things we need to do right."

This time a year ago, Croyle was designated as the foundation quarterback for Herm Edwards' rebuilding program. But Croyle missed almost the entire season with knee surgery and, when backup Damon Huard was also shelved with an injury, the job fell to Thigpen.

Croyle would certainly welcome the opportunity to win the starting job after spending several months getting over the surgery.

"You've got to be ready for it. This is what I've rehabbed for," he said. "This is what I've tried to get back for."

So far in preseason duty, Croyle has looked the best. In a dismal loss to the Seahawks on Saturday night with Thigpen playing most of the way, the Chiefs were 1 for 10 on third down.

"When you're (1 for 10) on third down, you're not getting it done at quarterback," Haley said. "There's just no way. Even if there are breakdowns at other places, the quarterback, it's his responsibility to move the chains. At (1 for 10), there really wasn't much good happening."

Thigpen, a former seventh-round draft choice, started 11 games last year and caused the Chiefs to switch their offense to a spread formation because he had trouble lining up and executing under center. This time last week, Thigpen was also the subject of trade rumors.

"That's the way this business works," said Thigpen, who took most of the snaps with the first team in practice on Monday. "You've got to be ready."

Johnson winces at memories of last year's 2-14 campaign.

"It was tough. We went through three different quarterbacks, then we had to change almost the whole offense to fit one quarterback's strengths. (Gailey) did well for what he was working with. It's not like we were out there with 11 Pro Bowlers."