The Chicago Cubs placed right-hander Mark Leiter Jr. on the 15-day injured list on Sunday because of a right forearm strain.
In a corresponding move, the Cubs recalled left-hander Luke Little from Triple-A Iowa.
Leiter, 33, has allowed eight runs over 3 1/3 innings in his last four appearances to raise his ERA from 3.20 to 5.34. He is 2-4 with 13 walks and 39 strikeouts in 28 2/3 innings over 32 relief appearances this season.
In parts of five seasons with the Philadelphia Phillies (2017-18), Toronto Blue Jays (2018) and Cubs (2022-present), Leiter is 8-21 with seven saves, a 4.65 ERA, 105 walks and 295 strikeouts in 274 2/3 innings over 183 games (15 starts).
Little, 23, was optioned to Iowa on Saturday. He is 2-1 with a 4.35 ERA, 17 walks and 20 strikeouts in 20 2/3 innings over 23 games (one start) with Chicago this season.