The Cubs are not willing to shut Carlos Zambrano down for the rest of the year.
The team said that the star pitcher is day-to-day after he left Monday's games with back spasms, but a shutdown is still possible. Zambrano had an MRI performed Tuesday.
"I want to pitch again, but I won't rush to come back because I could hurt the back some more or I could hurt my shoulder," Zambrano said. "I can't put my career at risk."
Zambrano likely took his name out of the Cy Young Award derby. He is 14-6 with a 3.50 ERA in 30 starts. He leads the National League with 188 strikeouts.
REPLAY: The Cubs had spent most of the season in fifth place in the National League Central. Now they are in sixth.
Pittsburgh scored a ninth-inning run off Ryan Dempster (1-8) for a 6-5 victory Tuesday night at Wrigley Field. Dempster is 0-3 and has allowed seven runs in four innings in his last four appearances.
The Cubs (55-83) had 15 hits on the night, with Derrek Lee and Juan Pierre each collecting had three hits and two stolen bases.
RHP Carlos Zambrano (back spasms) received an MRI on Tuesday, and the Cubs are taking it day by day with him until the pain subsides. He likely will miss his next start. RHP Jae Kuk Ryu or RHP Carlos Marmol could be in the mix to make Zambrano's start Saturday in Atlanta.
C Jose Reyes, a switch hitter, was brought up from Triple-A Iowa on Tuesday to serve as a backup to Henry Blanco and Geovany Soto in the wake of Michael Barrett's potential season-ending groin injury.
RHP Jae Kuk Ryu was promoted from Triple-A Iowa on Tuesday. It's his fourth stint with the parent club, and while he could be used for long relief, he may get in some starting duty with the uncertainty of the health of the pitching staff.
RHP Jerome Williams, who was in the starting rotation in April, was claimed off waivers by Oakland on Tuesday. When the Cubs sent him to Triple-A Iowa in May, they hoped he could be impressive in a few starts and return to the parent club. But he struggled and was demoted to the bullpen. He made it back to the starting rotation for Iowa, but didn't impress the Cubs brass enough to call him back up.
RHP Adam Harben was traded to the Cubs as the "player to be named" in the Aug. 31 deal that sent INF/OF Phil Nevin to Minnesota. Harben pitched in Double-A this year and is not expected to be called up to the parent squad this September.