Keuchel was scratched from his start Wednesday against the Royals due to an illness, Bob Nightengale of USA Today reports.
Dayan Diaz will draw his first major-league start in Keuchel's place. Keuchel was looking to go 10-0 to start the season, but that will have to wait until his illness subsides. If he's feeling better in the coming days, it's possible the Astros will move his next scheduled start forward.