Cubs manager Mike Quade is keeping right-hander Rodrigo Lopez in the bullpen for now, and he will return to the rotation on Saturday in St. Louis.
The rotation against the Brewers will be Dempster (7-7, 5.00 ERA) on Tuesday followed by Carlos Zambrano (7-5, 4.70 ERA) and Randy Wells (2-3, 6.17 ERA). Matt Garza, who started threw seven innings of a 5-4 win over the Astros on Sunday, will open the three-game set against the Cardinals on Friday followed by Lopez (2-2, 3.55 ERA) and Dempster.
Lopez has posted quality starts in his last three outings.
"He'd be available [in relief] even through the second game in Milwaukee," Quade said. "He's been pretty resilient. His experience is important."