CHICAGO — The Chicago Cubs placed Shota Imanaga on the 15-day injured list on Monday in another blow to an already depleted rotation for the NL Central leaders.

Imanaga, 31, strained his left hamstring when he went to cover first base in the sixth inning of Sunday’s 4-0 loss at Milwaukee. The Japanese left-hander has been one of the team’s most reliable starters since he signed a $53 million, four-year contract with Chicago in January 2024.

Imanaga had some imaging done, and he was slated to meet with team physician Dr. Stephen Gryzlo on Monday night.

“He feels pretty good today. … But I think we got to let the doctor look at him and let the imaging kind of guide us here,” manager Craig Counsell said.

Right-hander Gavin Hollowell was recalled from Triple-A Iowa before the opener of a three-game series against San Francisco. Hollowell, 27, threw two scoreless innings in his season debut with the Cubs on April 22.

Imanaga’s injury creates another hole in Chicago’s rotation. Left-hander Justin Steele is out for the season with an elbow injury, and right-hander Javier Assad has an oblique issue.

Imanaga pitched five-plus innings in his previous start at Pittsburgh before departing because of leg cramps. He is 3-2 with a 2.82 ERA in eight starts.

“You’re always building depth and you’re always dealing with injuries,” president of baseball operations Jed Hoyer said. “You always hope it’s not one of your best players, best pitchers, but that’s what happens. Hopefully we can figure out when we can get him back and get him back healthy. But we just got to step up. No one’s going to pause for us.”

Imanaga got hurt while covering first on a potential double play against the Brewers. He was in clear discomfort as he headed toward the bag. After the runner beat the throw to first, the pitcher grabbed the back of his left leg.

Imanaga said he had never had this kind of injury before.

“I think that’s the challenge is, with guys that have done those injuries before, they usually give you a better sense of how it feels compared to other times,” Hoyer said. “And he says he’s never been through this so a little bit of something new. But we’ll have to figure it out.”

The Cubs have some options when it comes to replacing Imanaga in the rotation, along with some flexibility because of their upcoming schedule. They are off Thursday each of the next four weeks.

Cade Horton, one of their top prospects, is 2-1 with a 1.24 ERA in six starts for Iowa. The right-hander pitched six innings of one-run ball against Buffalo on Sunday.

The Cubs also have veteran right-hander Chris Flexen, who has 110 career starts in the majors.

Imanaga’s slot in the rotation comes up again on Saturday at the New York Mets.

“I think we have options of how we decide to do that day,” Counsell said.

Imanaga went 15-3 with a 2.91 ERA in 29 starts last year, striking out 174 in 173 1/3 innings. He made the NL All-Star team and finished fourth in balloting for the NL Rookie of the Year.