The A's placed left-hander Felix Doubront on the 15-day disabled list on Monday with a sprained left elbow.
Outfielder Andrew Lambo was recalled from Triple-A Nashville to replace Doubront on the 25-man roster, but Oakland likely will make another move involving a pitcher before Doubront's scheduled start on Friday.
That likely will involve right-hander Jesse Hahn, who posted a 3.35 ERA in 16 starts for the A's last season but was slated to start the season with Nashville after posting a 11.15 ERA in Spring Training.
Doubront was removed from Saturday's exhibition against the Giants after just one inning with forearm tightness.
Lambo, 27, hit .333 with two home runs and five RBIs in 25 games this spring.