Holmberg gave up six runs in 2 2-3 innings of an 8-0 loss to Atlanta on Thursday night. In two starts for Cincinnati this season, the left-hander has faced 37 batters and allowed 21 of them to reach base: 12 hits, seven walks, two hit batters, four homers.
Corcino was called up from Double-A Pensacola. He'll make his big league debut the first time he pitches. Corcino went 10-11 with a 4.13 ERA in 25 starts and one relief appearance in the minors.
The 23-year-old will be in the bullpen initially with the Reds, who opened the day 10 1/2 games out in the NL Central.