Indianapolis Colts coach Chuck Pagano will be sidelined for several weeks with a “serious” illness, according to the Indianapolis Star.

Bob Kravitz reported this morning that Pagano, who is in his first season leading the Colts and is coming off a bye weekend, was feeling fatigued in recent weeks before undergoing blood tests that determined his illness. ESPN’s Chris Mortensen reported that Pagano has leukemia and it is “very treatable.” But that report indicates Pagano will be hospitalized for six weeks.

The Colts will hold a news conference this morning at 10:30 . Pagano will turn 52 on Tuesday. Offensive coordinator Bruce Arians is expected to assume control of the team in Pagano’s absence.

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Brad Biggs covers the Bears for the Chicago Tribune