Zambrano threw about 25 pitches on the side Thursday in Mesa. Cubs pitching coach Larry Rothschild and athletic trainer Mark O'Neal will monitor the pitcher's workout program.
"When he completes that, he'll be sent somewhere next week sometime," Cubs general manager Jim Hendry said of the next phase. "He has been throwing, he told us, but at the same time you have to monitor it yourself."
When Zambrano does return, he will be assigned to the bullpen. He has not thrown in a game since June 25, when he lasted one inning against the White Sox at U.S. Cellular Field and then threw a tantrum in the dugout, accusing his teammates of not playing behind him. He was suspended for three days and then placed on the restricted list.
There's no date set for Zambrano's return.
"He needs to get work in, and when our pitching people down there communicate with Larry that it's time to get him in some games, we'll send him to some," Hendry said.
How's Zambrano's attitude? Hendry said he didn't speak to the pitcher, but Zambrano (3-6, 5.66 ERA) did report ready to go.
"He's paid a dear price for his actions that day, and he'll act accordingly from now on," Hendry said of the Cubs' Opening Day starter.
There are no plans to break up the Cubs' rotation and insert Zambrano in there.
"We're just going to put him in the bullpen to start with," Cubs manager Lou Piniella said. "He's a ways away."