Chicago put Lester on the IL retroactive to Tuesday.
“We’re just going to play this as we go along,” manager Joe Maddon said. “Of course he’s going to miss his next start, but beyond that we’re just going to keep an open mind.”
Right-hander Tyler Chatwood will start in Lester’s place on Sunday against the Los Angeles Angels.
Lefty reliever Tim Collins was recalled from Triple-A Iowa on Wednesday. The 29-year-old is 0-0 with a 3.38 ERA in three games for Iowa. He pitched in 38 games for Washington last season.