"Hopefully in the postseason he will pitch very well for us, we need him to pitch well," the manager said.
"I said before I announced any pitcher that I had confidence in all four of my starters, so all games are equally important, and we chose to go this way," Piniella said. "Everybody's got to do their job now."
Fifth starter Jason Marquis will go to the bullpen and Zambrano, whose turn in the rotation would have come up Sunday, instead will throw a bullpen session on Monday or Tuesday to get ready for a Thursday start.
Piniella picked Dempster (17-6, 2.99 ERA) on Thursday to pitch Game 1 and the right-hander got his final tuneup before the postseason against the Brewers on Friday.
Piniella said there was no particular reason for putting Zambrano (14-6, 3.91 ERA) before Harden (5-1, 1.77 ERA) and Lilly (16-9, 4.17 ERA), and pointed out they really didn't know who their opponent would be.
"It's a fun time of the year," Piniella said. "It's what you play all year for. Hopefully this year will go a lot better in the postseason than last year."
Piniella also said he decided to carry 14 position players and 11 pitchers in the division series, but said the only spot still up for grabs was a final one in the bullpen. He declined to say who might be left off, but said Bob Howry, who has a 6.35 ERA in eight games in September, would be part of the postseason roster.
"When we're playing good, we're good," Piniella said. "We're going to pitch well and we've got to play good defensive ball then we've got to get some timely hitting. Obviously, I've got a lot of confidence in this team."