CHICAGO -- The Cubs couldn't win three in a row in their first 100 games. Now they can't lose.
Carlos Zambrano belted his 23rd career homer, Starlin Castro drove in a season-high four runs and Carlos Pena had three RBIs to power the Cubs to an 11-4 victory over the Reds on Saturday for their seventh straight win.
It's the longest stretch since Chicago won seven in a row from Aug. 23-29, 2008.
And Zambrano (9-6) has a streak of his own: He's now driven in a run and earned the win 38 times in his career, the most among active pitchers.
What's going on?
"You don't do it without contributions all over the place," manager Mike Quade said. "You don't do it without good starting pitching unless you're knocking the ball everywhere. To that point, we've been swinging the bats better."
The game didn't start well for Zambrano, who walked three straight batters with two outs in the first to load the bases before striking out Miguel Cairo to end the inning. Cairo got revenge in the third, when he and Yonder Alonso hit RBI singles to give the Reds a two-run lead.
"For some reason, the last two outings, Pittsburgh and today, I've been fighting with my mechanics and my arm slot," Zambrano said. "Hopefully, my next start, I will come with a better arm slot and a better feeling."
Zambrano felt good in the third when he homered, launching a 1-1 changeup from Johnny Cueto (7-5) into the right-field bleachers for his second of the season.
Zambrano never gets cheap homers.
"I'm not Campana, you know," he said, referring to the 5-foot-8 rookie Tony Campana, who on Friday hit an inside-the-park homer, his first in the Major Leagues. "I'm a big man. Inside-the-parkers I leave to Campana."
Zambrano's blast was the 13th by the Cubs in the last five games.
Two outs later, Aramis Ramirez singled, and he scored on Pena's double to tie the score at 2.
The Cubs batted around in both the fourth and fifth innings. Reed Johnson doubled to open the fourth, with the ball dropping between Drew Stubbs and Brandon Phillips, who collided in shallow center. Alfonso Soriano hit a tie-breaking RBI double, Geovany Soto singled and, one out later, Soriano scored on a fielder's choice.
Johnson's double was key.
"That was a big play that started everything in motion when Drew and Brandon collided," Reds manager Dusty Baker said. "That's a tough ball. ... They're both running with their heads up, looking at the ball, so they're not really hearing or seeing each other."
After a wild pitch, Cueto walked both Ramirez and Pena, forcing in a run and giving the Cubs a three-run lead. Cueto, who has a new Luis Tiant-style delivery, was pulled after giving up seven hits and three walks over 3 2/3 innings.
"It's tough from a timing standpoint and makes it a little bit different," Johnson said of Cueto's delivery. "He's had success doing it, so I'm sure he'll continue. Pitching is about mixing up a hitter's rhythm and trying to get them off balance, and I think that's a little way to do that."
The Cubs loaded the bases again in the fifth against Sam LeCure, and after Zambrano, who has never hit a grand slam, struck out, Castro hit a two-run double to make it 7-2. One out later, Ramirez hit an RBI single to Edgar Renteria, whose throwing error allowed another run to score.
"Any time you win, it's fun," Pena said. "We've been winning, so it's just a blast. Everything feels a little bit lighter. It's a lot of fun to watch the fans get into it, too. It's good energy going on all around."
Castro now has scored a run in eight straight games, and he is in the middle of a seven-game hit streak in which he's batting .500 with seven RBIs and five multi-hit games. His four RBIs are the most since he drove in six in his debut on May 7, 2010, at Cincinnati.
"He's done a good job," Quade said. "I always lean toward the defensive end, because the offensive end has been good for quite some time. He continues to work to try to become a better shortstop, too, and that's a big plus."
Quade is considering giving the 21-year-old shortstop a day off.
"But not right now," he said.
The Cubs are now 6-0 in August for the first time since they began August 1969 with six straight wins. In 1909 they opened the month 7-0 en route to a 9-0 streak; they began August 1927 with seven wins as part of an 8-0 spurt.
"We've been doing the right things and playing good defense," Zambrano said. "We've been doing things that everybody expected from us. That's what this team is capable of doing. We have a good team, we have a great team. We need to go and compete every day like we've been doing the last seven days and have fun. That's a key for us -- have fun and enjoy the game."
Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter@CarrieMuskat. This story was not subject to the approval of Major League Baseball or its clubs.