Guard Brian Waters and receiver Dwayne Bowe, two of Kansas City's three Pro Bowlers, missed Wednesday's practice and it was unclear whether they will be available for this weekend's playoff game against Baltimore.
"Waters and Bowe will be listed as illness. They were sick today," coach Todd Haley said.
How sick was anyone's guess. But the Chiefs signed free agent wide receiver Kevin Curtis, who has played in 81 games with Miami, Philadelphia and St. Louis.
Sticking to the team's policy of not commenting on player availability, Haley declined to speculate on whether Waters or Bowe would be ready for Sunday's home game against the Ravens.
"I just go by today. Today they were not able to go," he said.
Last month, Haley used the word illness to explain quarterback Matt Cassel's absence from practice. The Chiefs then disclosed that Cassel had undergone an emergency appendectomy that wound up sidelining him for a game.
The Chiefs are coming off a home loss to Oakland in which their offense struggled and will now face the rugged Baltimore defense.
Waters was named to his fifth Pro Bowl and has long been recognized as one of the Chiefs' top leaders.
Losing Bowe would really hurt — he is the Chiefs' only consistent threat at wide receiver and was named to his first Pro Bowl after making 72 catches for 1,162 yards and a league-best 15 touchdowns. Between Oct. 17 and Nov. 28, he also set a team record with at least one touchdown catch in seven straight games.
If Curtis is pressed into service against Baltimore, Haley said he was confident he can do the job.
"We've done a lot of research on this guy throughout the year. But it's our effort to always make progress and create competition," Haley said. "He knows this system. What they're running in Miami is very similar terminology. That's an edge."
Cassel said Bowe's missing a day or two of practice should not disrupt their timing.
"We've been together for 17 weeks now, or whatever it's been, and hopefully he's back sooner than later and he rests up and he's back on the field and we're able to continue to work together," Cassel said. "From a timing standpoint, I think I understand Dwayne's body language, his ability to run certain routes. I think we'll be fine."