Kansas City, Mo. ? The Kansas City Chiefs will have to wait a bit longer before they know when quarterback Matt Cassel will return from an appendectomy.

Cassel had emergency surgery last week and did not play Sunday for the AFC West leader’s 31-0 loss at San Diego. Cassel said he is day-to-day, and was at the Chiefs’ practice facility working out Monday after not traveling to California over the weekend.

“(Today) we’ll know a lot more,” Chiefs coach Todd Haley said on whether Cassel would be able to play against the Rams on Sunday.

Despite the loss, the Chiefs remain in first place in the AFC West with a one-game lead over the Chargers with three games left, so they control their own destiny.

“Exactly, absolutely right,” defensive end Wallace Gillberry said. “There were some things we could have done better (at San Diego), but we didn’t, so it’s on to the Rams. This is not our first road loss and we’ve come back and taken care of business. That’s what we are banking on, to comeback and get back on track, focus on the Rams.”

After St. Louis, the Chiefs’ final two regular season games are at home against two sub-.500 teams, Tennessee and Oakland. The Chiefs are undefeated at Arrowhead Stadium this season.

If the Chiefs had won at San Diego, they would have all but wrapped up their first division title since 2003 with a three-game lead with three games remaining.

“It was a very disappointing result in what was our biggest game of the year,” Haley said. “This (St. Louis) now becomes our game of the year. We’ve got to move on. We’ve done a good job of doing that after a win or a loss.”

Haley said the Chiefs would “not dwell” on the lopsided defeat at San Diego.

“Our focus is trying to become a good team,” Haley said. “We’re clearly not there yet. That team we played (Sunday) is in that category and has been for a number of years.”

With Brodie Croyle replacing Cassel as the starting quarterback, the Chiefs had only 67 yards of offense, went 0-for-11 on third down conversions, mustered just 19 yards passing, punted eight times and had the ball for only 19:50.

The Chiefs are 0-10 when they start Croyle, a 2006 third-round pick from Alabama. It was his first start since Sept. 13, 2009, at Baltimore when Cassel was injured.

Haley said he has confidence in Croyle to lead the Chiefs to a victory if Cassel is unable to play again.

“He’s disappointed,” Haley said. “He wanted to do better.”