The Chicago White Sox placed right-hander Michael Kopech on the 15-day injured list Friday with right knee inflammation.
Kopech, 27, had surgery Friday morning to remove a cyst from the knee and faces a recovery time of 6-8 weeks.
He finished his fourth season in Chicago with a 5-12 record and a 5.43 ERA in 30 games (27 starts).
The White Sox recalled right-hander Yohan Ramirez from Triple-A Charlotte to replace Kopech on the roster.
Ramirez, 28, was signed off waivers from the Pittsburgh Pirates on Sept. 5 and has not yet pitched for Chicago.