On Friday, it was Zambrano (11-7) who led the way.
Big Z gave up three hits while striking out seven over 6 2/3 scoreless innings, and became the National League's first 11-game winner. He also added an RBI single, and is now 6-2 with a 1.55 ERA since June 6.
"He's in that groove right now where he gives you a chance to win everytime he's out there," manager Lou Piniella said. "Anytime your No. 1 starter picks it up like he has, it gives you a big lift as a team."
Zambrano's teammates were not shy about the pitcher's role on the team.
"What you're seeing now is just the talent coming out, pitching the way he's supposed to pitch, and knowing that if we want to win, if we want to do anything, it's going through Zambrano," Cliff Floyd said. "At the end of the day, having him in our rotation alleviates a lot of problems."
One of those problems is the Cubs' recent lack of home runs. Friday's game was the 10th straight in which they were homerless, the longest such drought since July of 1988. The last time the Cubs went 11 games or more without a home run was when they went 15 games without a long ball, from July 15-28, 1978.
Despite the power outage, the Cubs have been finding ways to win.
"The biggest key is scoring runs, that's the name of the game," Derrek Lee said. "So if you do it with a single, double or home run, it doesn't really matter. A home run does make it easier to score some runs quicker, but we're getting the job done without the home run right now."
The Cubs took a 3-0 lead in the fourth, thanks in part to the Astros committing two errors on the same play. Floyd led off with a single, advanced to third on Mark DeRosa's single, and scored on Jacque Jones' sacrifice fly to left.
Then came the wackiness. With DeRosa at second, Geovany Soto, who was recalled from Triple-A Iowa on Friday, hit a hard grounder to third baseman Mike Lamb. Lamb's throw to first got by Lance Berkman, and DeRosa advanced 90 feet. Berkman then tried to pick off DeRosa, who had overrun third, but his throw sailed into the stands, which allowed DeRosa to score and advanced Soto to third. Soto scored the next at-bat on one of Zambrano's two singles.
The errors were two of a season-high four committed by the Astros, who had no answers for Zambrano.
"It's not like we came out against somebody's No. 5 starter and were shut out," Berkman said. "You're facing probably the guy with the best stuff in the National League on a day that the wind's blowing straight in here at Wrigley Field, where you're not going to get any base hits on the ground and there's going to be no base hits in the air.
"You're pretty much going to have to hit line drives and he doesn't walk many guys," Berkman said, "so we certainly are disappointed that we lost and we played some sloppy defense which is never good."
The Cubs loaded the bases in the sixth, and Chad Qualls walked Aramis Ramirez to make it 4-0.
Zambrano was pitching well through the sixth, not allowing a runner in scoring position. But in the seventh, he ran into some trouble. Zambrano gave up a single to Carlos Lee and walks to Mark Loretta and Luke Scott before being pulled by Piniella. Carlos Marmol came in and induced Eric Munson to fly out to end the inning and preserve Zambrano's shutout.
Lee gave the Cubs a cushion with a two-run double in the eighth. The hit was the closest the team got to a home run all day.
"We put six runs on the board today, we got really good pitching, we played a good defensive game," Piniella said. "We didn't need the home run ball today. Hopefully, when we do need it, it will come."