Piniella said the order would most likely not change depending on who the Cubs face in the first round of postseason play. Asked if a pitcher's home and road records helped him make the decision, Piniella paused.
"Let's not get too technical," he said. "It's those four. Everybody's got to do their job now."
Jason Marquis, who is 11-9 with a 4.43 ERA in 28 starts, will be in the bullpen for the postseason. The Cubs will carry 11 pitchers.
"We're probably still playing around with one spot [in the bullpen]," Piniella said. "That's it."
One reliever who has secured a spot is Bob Howry, who is 7-4 with a 5.17 ERA in 71 appearances this season.
"I need Bob to pitch well," Piniella said. "I had a nice little meeting and told him we need him to get nice and sharp and pitch well for us."
Zambrano most likely will not pitch in the final regular-season games at Miller Park, site of the right-hander's no-hitter on Sept. 14.
"He competes," Piniella said. "Sometimes it detracts away from his abilities. Hopefully, in the postseason, he'll pitch very well for us. We need him to pitch well."
The Cubs have yet to determine the final position players who will be on the playoff roster. Micah Hoffpauir, who went 5-for-5 with two home runs and five RBIs on Thursday against the New York Mets, was in the starting lineup on Friday.
"Let me see who our opponent is going to be," Piniella said. "Let me see how they're constituted and how we match up. We'll wait a little bit on that. I think that will clarify as this weekend goes by."
The Cubs could open the NLDS against the New York Mets, Philadelphia Phillies or Los Angeles Dodgers. Does Piniella have a preference?
"No preference," he said. "Regardless of whoever gets in, for us to get done what we want to accomplish, we'll have to beat them the first or second round. We have to be ready to play."