Zambrano went on the 15-day disabled list on May 4, a day after he strained his left hamstring trying to beat out a bunt. He is scheduled to pitch Sunday in Clearwater, Fla., before starting against San Diego on May 22.
"Carlos had a nice bullpen session," manager Lou Piniella said before Chicago played the San Diego Padres. "He threw the ball well. It was encouraging."
Zambrano told ESPNChicago.com that he will throw 75 to 80 pitches on Sunday. When he does get back, however, he said he will take it easier on the basepaths.
"I'm not going to be like Juan Pierre or Jose Reyes in the beginning," he told ESPNChicago.com. "I'm going to be more like Geovany Soto or Bengie Molina. I must take it easy.
"After that, I'm going to be the same I was. After one month I will be the baseball player I've always been."
Ferrero beats Serra to win Casablanca final
Ferrero beats Serra to win Casablanca final
Source: MLB fines Bobby Jenks of Chicago White Sox $750 for purpose pitch
