ATLANTA -- Horacio Ramirez wanted to prove his previous poor outing was an exception.
"Today I had a good fastball," he said. "I threw it. I didn't guide it. I threw it with conviction."
Ramirez pitched his first career shutout, and the Atlanta Braves chased Mark Prior in the fifth inning of a 6-0 victory Thursday that sent the Cubs to their seventh straight loss in the opener of a day-night doubleheader.
It is the second time this season the Cubs have lost seven consecutive games. This run matches their longest skid since dropping nine straight from May 8-18, 2002.
Ramirez went 3-4 with a 5.65 ERA in nine starts during the first two months of the season, but he recovered to go 4-0 with a 3.55 ERA in six June starts. He lasted just 4 2/3 innings in his previous outing, a 6-3 loss at Philadelphia last Saturday.
Ramirez (8-5) tossed his third career complete game and first since May 20, 2004, against Arizona. The left-hander allowed just three singles and one walk.
"This is when he's at his best, when he's getting quick outs," Braves catcher Johnny Estrada said. "When they know he's going to be around the plate, they will be aggressive."
Julio Franco hit a three-run homer in the five-run fifth for the Braves, who won for the 15th time in 20 games. Rafael Furcal had a run-scoring double, and Andruw Jones hit an RBI single before the 46-year-old Franco's seventh homer of the season.
"You want to score a lot of runs when you're facing Prior," Franco said. "If he gets two or three runs, it's hard to beat him."
Prior (5-3) gave up seven hits, six runs, four walks and struck out five before being replaced by Sergio Mitre with two outs in the fifth. Chicago starters have a 6.75 ERA in the Cubs' 43 losses this season.
"They did some things with some good pitches and just kind of waited for a big break, which they got," Prior said. "I had a tough time throwing my curveball for strikes. In fact, I didn't have a curveball at all, so I think going out there throwing pretty much two pitches, it's tough against this lineup."
Todd Walker, starting at first base in place of injured Cubs All-Star Derrek Lee, singled in the second and walked in the fourth. Jeromy Burnitz singled in the seventh and Michael Barrett in the eighth for the only baserunners Ramirez allowed.
The Braves outscored the Cubs 15-1 in the first three games of the four-game series.
"We've played three games here, and we've got one run," Chicago manager Dusty Baker said. "That makes it tough. This is a tough period we're going through right now. It hurts not to have D. Lee in there, especially against a left-hander. We've got to change something."
Ramirez improved to 1-1 in three starts against the Cubs after entering with a 5.91 ERA when facing Chicago.
"I was throwing more first-pitch strikes than usual," Ramirez said. "If I got behind in the count, I could throw a two-seamer. I'd been throwing cutters that didn't cut. I was able to minimize those today."
Prior, facing the Braves for the third time and first since 2003, dropped to 0-3 with a career ERA of 7.88 in 15 innings against Atlanta.
Baker said the Cubs wouldn't have Lee for the second game, either, but Prior refused to blame the hitters for the team's struggles.
"It's not our job to worry about the offense," Prior said. "Our job's to go out and worry about their offense. It's all I do, and obviously I didn't have a good game today. I don't know how much else to put it."
After returning June 26 from a non-displaced fracture in his right elbow, Prior pitched six shutout innings to beat the White Sox 2-0, but he has lost two straight starts.
Ryan Langerhans gave the Braves a 1-0 lead with a sacrifice fly in the second.
- The Cubs also lost seven straight from April 30-May 7.
- Atlanta manager Bobby Cox changed course and said rookie Jeff Francoeur would start the second game in right field. Cox stated Wednesday night that Francoeur, whose contract was purchased from Double-A Mississippi, wouldn't debut until Friday.
- Braves starters Tim Hudson and Mike Hampton said they will pitch another simulated game Saturday instead of making a rehab start in Class A.
- The Cubs are 13-21 at Turner Field.