The focused Cubs took care of business with an 8-4 win over the Atlanta Braves on Saturday night to continue their recent strong play. Chicago has won 10 of 13.
Manager Mike Quade said he wasn't surprised when his team responded to the controversy with a win.
"You know what? I'm never surprised at these guys," Quade said. "They just come to the park and play.
"They just go about their business. And that's a good thing. No distractions. Let's just play."
Atlanta's Dan Uggla had two hits, including a homer, to extend his hitting streak to 33 games, the longest in the majors this season.
Cubs general manager Jim Hendry said Zambrano would receive no pay and have no part in team activities for 30 days.
Zambrano cleaned out his locker and left the team after giving up five homers and being ejected from Friday night's 10-4 loss to the Braves. He did not return to the team Saturday.
Hendry said Saturday that Zambrano's actions were "intolerable."
"This was the most stringent penalty we could enforce without a release," Hendry said.
Cubs pitcher Ryan Dempster had similarly strong words.
"He's made his bed. Let him sleep in it," Dempster said.
"It's not like it's something new."
Randy Wells (4-4) gave up two runs on eight hits in five-plus innings.
"Just a normal day," Wells said. "Try to forget about last night.
"I haven't heard the whole story. I've tried to stay out of it. I really don't even feel comfortable talking about it. I don't know the details."
Derek Lowe (7-11) gave up five runs on 10 hits in six innings. He allowed three hits, including Pena's two-run double that gave Chicago a 3-1 lead in the fifth.
Quade brought in closer Carlos Marmol, who gave up a long fly ball to Chipper Jones to drive in Prado before ending the game when Alex Gonzalez hit a pop fly to Castro at shortstop. Marmol earned his 27th save.
The Cubs added two runs in the sixth. Tyler Colvin led off with a triple to center. Atlanta's Michael Bourn had the long drive in the top of his glove before losing the ball when he crashed into the wall.
Colvin scored on Geovany Soto's grounder to third. Chipper Jones threw high to the plate and was initially charged with an error. After the game, Soto was awarded an RBI when the error was changed to a fielder's choice grounder. Soto scored on Castro's single.
A fielding miscue by left fielder Martin Prado hurt the Braves in the eighth. After Alfonso Soriano led off the inning with an infield hit, Colvin hit a liner that skipped off the charging Prado's glove for an error, allowing pinch-runner Tony Campana to advance to third.
Right-hander Cristhian Martinez fielded pinch-hitter Blake DeWitt's grounder and threw to the plate, but Campana slid under Ross' tag. Castro and Barney added run-scoring singles.
Hendry said Major League Baseball and the players' association would discuss Zambrano's statements about his baseball future.
Quade said Friday night that Zambrano told team personnel he might retire.
Asked if he knew where Zambrano was on Saturday, Hendry said: "I have no idea."
Cubs third baseman Aramis Ramirez said Zambrano would be welcomed back by his teammates, but only if he made changes.
"If he changes his attitude, he's more than welcome," Ramirez said.
"He's got to think a little bit more. He's one man. It's not just one time. A lot of people have tried to help him. He won't let them."
Zambrano was placed on the restricted list for six weeks and sent to anger management last season after a verbal altercation with then-teammate Derrek Lee.
In 2009, he was suspended following a tirade against an umpire in which he threw a baseball into the outfield and slammed his glove against the dugout fence.
In 2007, Zambrano signed a deal adding $91.5 million over five seasons through 2012. He was to earn $17.85 million this season and $18 million in 2012.
He is 9-7 with a 4.82 ERA.
A message was left Saturday seeking comment from Barry Praver, Zambrano's agent. Hendry said Praver indicated Zambrano is not retiring.
The Cubs did not immediately announce a corresponding roster move for Zambrano. The team will need a starting pitcher for his next scheduled turn in the rotation Wednesday at Houston.
NOTES: The Braves had a pregame video tribute for former radio and TV broadcaster Ernie Johnson Sr., who died Friday night at the age of 87. Johnson was involved with the team for more than 50 years as a player, executive and broadcaster. ... A collection of players from the Braves' 1991 NL championship team took a 7-7 tie in a softball game against former Braves players from other years. John Smoltz hit a two-run homer and made an over-the-shoulder catch in center field for the 1991 team, which was managed by Bobby Cox. Many of the players attended Friday night's ceremony to retire Cox's No. 6. ... Braves rookie Brandon Beachy will try for his sixth win against Chicago's Matt Garza in Sunday's final game of the series. Garza will be making his first career start against Atlanta, and Beachy will make his first start against the Cubs. ... Braves C Brian McCann expects to return from a strained left oblique injury Sunday. He played his second rehab game with Triple-A Gwinnett on Saturday. ... Castro matched his career high with his four hits
AP freelance writer Amy Jinkner-Lloyd in Atlanta contributed to this report.