CHICAGO -- The Chicago Cubs placed right-handed starter Keegan Thompson on the 15-day IL Saturday with low back tightness and recalled righty Anderson Espinoza from Triple-A Iowa.

The 27-year-old Thompson leads the Cubs in wins with a 9-5 record and 3.97 ERA in 25 games. He has made 17 starts since joining Chicago's rotation on May 11.

Manager David Ross doesn't believe Thompson's injury is serious, but said it affected the righty on Friday against Milwaukee when he allowed five runs - all from home runs - in 3 2/3 innings in a second straight shaky start.

"Is it something we're super long-term concerned about? No," Ross said before Saturday's rain-delayed game against the Brewers. "It makes a lot of sense to make sure we take care of this, this doesn't pop up to be something major."

Thompson has pitched 104 1/3 innings this season, the most for him since 2018 in the minors. He's in his second year in the majors.

Espinoza was recalled from the minors for the sixth time this season. He is 0-2 with a 4.11 ERA in six games with the Cubs in 2022.