KANSAS CITY, Mo. (AP) -- Rookie head coach Todd Haley fired offensive coordinator Chan Gailey and assumed that role himself Monday, 13 days before he opens the season with a very unsettled quarterback situation.
Matt Cassel was injured in Saturday night's preseason loss to Seattle, limping away with a knee injury. But Haley refused to discuss the injury to Cassel, who signed a six-year contract for a guaranteed $28 million.
Yahoo! Sports, citing a source in the organization, reported Cassel sprained the medial collateral ligament in his left knee and could miss two to four weeks.
The top candidates to replace Cassel are Tyler Thigpen and Brodie Croyle, who are 1-18 as starting quarterbacks in the NFL. Thigpen took about 80 percent of the snaps with the first team in practice Monday, but a decision could be based on who plays well in the final preseason game at St. Louis on Thursday night.
Haley, the offensive coordinator at Arizona the past two years, declined to say whether the offense will make any significant changes before beginning the Sept. 13 season opener at Baltimore. He also will serve as quarterbacks coach.
"That is something I put a lot of thought into," he said. "The advantage I have now is I know pretty much what my duties are. ... Obviously, I think this is best for the team."
Gailey, a 16-year NFL coaching veteran, joined Kansas City in 2008 as offensive coordinator under Herm Edwards. Haley said he would be offered another job within the organization.
"I think the world of Chan as a coach, have the greatest amount of respect for him as a coach, as a person," Haley said. "But ultimately, the fate of this team, the accountability, falls to me."
A clash between Haley and Gailey seemed inevitable to running back Larry Johnson.
"It's like my mother says -- too many roosters in the henhouse, so to speak," he said. "Two coordinators and both passionate about what they do and passionate about how they want to call plays."
In a statement released by the Chiefs, Gailey said there was "never great timing for situations like this."
"However, Todd has to do what's best for the team and for the future of the Chiefs. I respect that," Gailey said.
The Chiefs, 2-14 last year, are 0-3 in the preseason and have scored only two offensive touchdowns.
A year ago, Croyle was the Chiefs' designated starter for Edwards' rebuilding program. But injury-prone, he made only two starts before going down with a knee. Then backup Damon Huard also sustained season-ending injuries, leaving third-teamer Thigpen, a former seventh-round pick, to go 1-10 in 11 starts.
"To me, it seems like deja vu five times over," Johnson said. "It happened with Trent (Green in 2006), it happened with Brodie, it happened with Damon."