DENVER -- Right-hander Jordan Lyles, who pitched five innings in the second game of Monday's doubleheader loss to the Rockies, was optioned to Triple-A Oklahoma City on Tuesday.

The Astros, who were swept by the Rockies in Monday's twin bill, had called up Lyles to be the 26th player on their roster for a day, taking advantage of a new rule that allows an extra player to be added for doubleheaders.

Lyles (0-1, 5.73 ERA) gave up six hits and six runs (four earned) in his fourth start with the Astros. He has had three different stints with Houston, getting called up three times when the Astros were in need of a fifth starter. They will need a fifth starter again on Sunday.

Lyles, 21, made 15 starts for the Astros last year and appeared in 20 games total, going 2-8 with a 5.36 ERA in his Major League debut season. He's 5-0 with a 3.54 ERA in seven starts this year at Triple-A Oklahoma City.