The Cleveland Guardians placed right-hander Shane Bieber on the 15-day injured list Saturday because of elbow inflammation in his pitching arm.
The news comes one day after Bieber had an MRI exam.
"For about the last month, [his] forearm has been kind of irritable, but we felt like he was trending in the right direction," Guardians manager Terry Francona said. "For [a few] starts there, I think we held him to like 80 pitches. But the last couple [starts], he wasn't comfortable with the way he's bouncing back."
Also on Saturday, Cleveland recalled right-hander Michael Kelly from Triple-A Columbus.
Bieber, 28, is 5-6 with a 3.77 ERA in 19 starts this year, but he is 0-3 with a 5.22 ERA in his past five outings.
He most recently pitched on Sunday, when he gave up four runs on nine hits in 6⅓ innings during a 4-1 loss to the visiting Kansas City Royals. Bieber struck out six without issuing a walk.
Bieber was the 2020 American League Cy Young Award winner after going 8-1 with a 1.63 ERA in 12 starts during the pandemic-abbreviated season. The two-time All-Star has a career 59-32 record with a 3.26 ERA in 132 games (130 starts).
Kelly, 30, is 1-3 with two saves and a 2.73 ERA in 27 relief appearances this season with Columbus.