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.

Chicago's bullpen subsequently allowed a pair of inherited runners to score, impacting Imanaga's line for the worse. The book closed on his afternoon with him surrendering two runs on four hits and a walk. He also struck out four of the 22 batters he faced.

The Chicago Cubs will be without their top starter for at least the next two weeks. Left-hander Shota Imanaga went on the 15-day injured list Monday.