Zambrano threw 73 pitches Monday in a simulated game at Wrigley Field, his first extended outing since switching to the bullpen on April 22. Zambrano is being stretched out so he can return to the rotation.
Cubs manager Lou Piniella said Sunday that Zambrano's first start would be on the road, which means he would miss the upcoming series against the Dodgers and Cardinals that opens Tuesday night. The Cubs begin a nine-game trip on May 31 in Pittsburgh.
No stats are kept during a sim game except the pitch count. Jeff Baker and Tyler Colvin faced Zambrano in the workout.
Zambrano was 1-2 with a 7.45 ERA in four starts, and he is 0-1 with a 4.76 ERA in 11 relief appearances. With the right-hander getting ready for a rotation return, the Cubs will be short-handed in the bullpen.
Carrie Muskat is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.