Zambrano (3-6, 5.71 ERA) has made two appearances since being activated from the restricted list Friday, including a 53-pitch, two-inning outing Sunday. Manager Lou Piniella said the right-hander could go 75 or 80 pitches in San Francisco.
"Let him pitch," Piniella said.
In his last start June 25 against the White Sox, Zambrano gave up four runs in the first inning, then threw a tantrum in the dugout. He was suspended for three games and placed on the restricted list to undergo treatment for anger issues.
"I think everything is going absolutely fine," Piniella said.
Being sidelined for more than a month has made Zambrano appreciate his job even more.
"Sometimes you don't know what you have until you lose it," he said. "When you lose it, you realize you have something good in your career, your life, and I don't want to lose this opportunity.
"I want to take advantage of it and be prepared for the last two months," he said. "I just want to pitch here, be happy here in Chicago. I just want the people to be happy. The way to do that is to pitch good."
In nine starts this year, including an Opening Day loss to the Braves, Zambrano was 3-5 with a 6.12 ERA. What was encouraging about his outings in Colorado was that Zambrano's velocity was improved.
"The last two outings, I just threw the ball as hard as I could," he said. "Sometimes I try to be too perfect. That's not me. I've been watching videos and watching myself pitching. I think if I throw the ball and let the ball do the movement and throw as hard as I can -- I was throwing with [Carlos] Silva and throwing a four-seamer and the ball was still moving. That's a privilege, that's what God gave me. I have to use it.
"Like Larry [Rothschild, the pitching coach] said, I have to throw the ball no matter what and don't try to locate it," Zambrano said. "It's good to locate a pitch, but with the kind of movement I have, it's good to throw the ball and see what happens."
He even revived his cutter against the Rockies, getting Brad Hawpe to pop up in the seventh inning Saturday.
"If I can have more good pitches to dominate in this league, I will have them," he said.
It's been a wild ride for Zambrano this year. He made his sixth Opening Day start, but lost, and went 1-2 in his first four starts before switching to the bullpen to make room in the rotation for Ted Lilly when he was activated from the disabled list.
Zambrano made 13 relief appearances but told the Cubs he wasn't comfortable in the role, and was he inserted back into the rotation for five more starts, ending June 25.
Piniella has supported Zambrano through the roller-coaster ride.
"I appreciate that," Zambrano said. "That's how the manager has to be, just be aware we're human and make mistakes. We listen to him, and thank God everything is going in a good way right now."
Although he said he would approve a trade if the Cubs decided to move him, Zambrano made it clear he wants to stay in Chicago.
"I came with a mission, and I never quit," he said. "For me to be traded, it's like quitting. I love this city. I think this city deserves to watch a game in the World Series. This city deserves -- these fans deserve -- to celebrate a championship with us. That is what I'm here for. We'll do it, sooner or later. That's what we're here for is to win, win everything and do the best we can. This city needs it. This is special."
Zambrano said he has gotten nothing but support from his teammates since his return.
"I appreciate all the love my teammates have given to me," Zambrano said. "I think we are like soldiers. When somebody goes down, it can happen to anybody on this team, or something could happen to some of us -- not anger management but something, and if that happens, I'll be the first one to support him, I'll be the first one to carry him. That's the way we are in this clubhouse."
He's not finished with his therapy sessions, but his focus now is trying to finish strong and be better than he was. Zambrano won 18 games in 2007, then 14 in '08 before struggling through a 9-7 season last year.
"We have two months to go and we have faith -- at least I do -- to turn it around," Zambrano said.