7/7 Demp, Z, Mateo & Bake

Ryan Dempster threw what he jokingly called an “epic” side session on Thursday and said he expected to start the second game of a three-game series against the Pirates on Saturday. Dempster missed his Monday start because of back soreness and stomach problems. He was hospitalized overnight for observation on July 2. But on Thursday at Nationals Park, he was able to do a normal side session in the bullpen and then went for a run with pitcher Chris Carpenter.

“As long as I feel good [Friday], I don’t see any reason why I can’t pitch on Saturday,” Dempster said.

* Carlos Zambrano, on the disabled list with lower back soreness, will make a rehab start on Friday for Class A Peoria. If all goes well, Zambrano could be back in the Cubs rotation for a July 16 start against the Marlins. Mike Quade’s brother Scott caught Zambrano in a side session on Wednesday at Wrigley Field.

“If you’ve caught him before then you know what a Zambrano side is like,” Quade said. “[My brother] told me, ‘He’s the same as the guy I caught last year’ and thought he threw fine. It was a productive day for [Zambrano].”

* The Cubs expect MRI results on Marcos Mateo’s right elbow on Friday. He went to Chicago for the test.

* Jeff Baker was questionable for Thursday’s game. He’s trying to return from back spasms.

– Carrie Muskat