The Cubs dropped to 5-9, and have now lost seven of their last nine games. Atlanta has won three of its last four.
Derrek Lee had a pair of doubles, and Mark DeRosa homered and drove in two runs, but the only fresh arm in the over-worked bullpen, which had thrown nine innings the day before but could not hold the lead.
Scott Eyre (0-1) took the loss, allowing three runs on three hits and two walks in 2/3 of an inning. The Atlanta uprising was particularly demoralizing because it came the half-inning after Chicago had rallied for a 6-5 lead, and all the damage came with two outs.
Oscar Villarreal (1-0) blew a save, but got the win for Atlanta. Bob Wickman got his fifth save in five opportunities by pitching a perfect ninth.
Eyre, who pitched out of a bases-loaded, two-out jam on Tuesday afternoon against San Diego, would not be as lucky this time. Braves second baseman Kelly Johnson hit a two-run single to right, then shortstop Edgar Renteria followed with an RBI single to left, increasing the lead to 8-6.
"Bad pitches," said a disconsolate Eyre, who had been not been scored upon in his previous three appearances. "The pitch to Renteria was up. We wanted it up, but it wasn't high enough. The pitch to Johnson was basically just a slider over the middle of the plate and he hit it. I made some mistakes. Every time I seem to make a mistake, it costs [us]."
The Cubs, who had rallied from a pair of three-run deficits, appeared ready to rally again, putting runners on second and third in the eighth, and even had reliever Peter Moylan sling a pitch past McCann. But a lucky bounce off the backstop kept runners from advancing. Then, after an intentional walk loaded the bases, Ryan Theriot's smash to short was turned into an inning-ending 6-4-3 double play.
Zambrano got a no-decision and now has one win in four starts. He pitched six innings, allowing five runs (all earned) and eight hits, striking out six and walking five (one intentional). He also walked the tightrope all night, putting at least one runner in scoring position in every inning, yet managed to escape.
He got a key double play grounder from Chipper Jones to end the second inning, retired Atlanta starter Kyle Davies on a comebacker with the bases loaded in the third, and retired Andruw Jones on a grounder to third to end the fourth and a ground ball to short to end the sixth.
The only jam he couldn't escape was in the first inning, when he walked Andruw Jones after jumping ahead 1-2, then allowed an RBI single to McCann and a three-run homer to Francoeur on the next two pitches as the Braves took a 4-1 lead.
"In the first inning, I wasn't feeling good, I wasn't hitting my spots," said Zambrano, who currently is pitching to a 7.77 ERA (19 earned runs in 22 innings). "That's why I was fighting myself. But after that, I came back and did my job and shut the door."
"I told him to try to hold his composure on the mound," said manager Lou Piniella. "Quit fighting himself and concentrate on the hitter."
While fighting himself and fighting through the jams, Zambrano allowed the Cubs to chip away at the lead.
Felix Pie's triple and DeRosa's groundout cut the lead to 4-2. Then, after a Scott Thorman homer made it 5-2 in the fifth, the Cubs knocked Davies out of the game in the sixth inning, stringing together three straight hits, including an RBI double by Aramis Ramirez and an RBI single by Cliff Floyd to cut the lead to 5-3. Michael Barrett's sacrifice fly off reliever Tyler Yates scored Ramirez to cut the lead to 5-4. But after an infield hit by Jacque Jones, Cesar Izturis struck out to end the threat.
They took the lead in the seventh, but saw Atlanta come back off Eyre.
"I let our bullpen down," said Eyre. "[Neal Cotts] needed a day off, and he had to come in and get me out of a jam and pitch another inning. He didn't need to do that. I need to step up and finish that inning myself."
DeRosa drove in the first two Chicago runs in his return to Turner Field, where he'd played as a Braves infielder for six seasons. DeRosa gave the Cubs a 1-0 lead by hammering a 1-0 pitch from Davies into the seats in left-center field for his fourth homer of the season.
Jacque Jones added two hits and Pie, playing in his second game in place of injured Alfonso Soriano, tripled and scored two runs.
Zambrano assured that better days are ahead for him.
"I guarantee you I won't finish like this," he said. "I've said it many times, it's not how you start, it's how you finish."
Piniella is as confident that tomorrow's finish also would be different.
"We came back at them and I'm proud of the guys," he said. "The only fresh pitcher I had in the bullpen was Scott Eyre, and he just didn't get the job done. But we rested everybody else. We should be in better shape tomorrow."