Dempster (8-2) struck out 11, gave up four hits and walked none. But the win came at a hefty price. Alfonso Soriano was taken out of the game after being hit by a pitch on the left hand and breaking his left ring finger in the second inning. The injury will keep him out for about six weeks.
"That's a real bummer," said Dempster, who is 8-0 at Wrigley. "It's hard to sit back and enjoy your victory when one of your best players and one of your leaders on your team goes down."
The bats came through without the star left fielder. Runs scored in the first three innings, courtesy of a Kosuke Fukudome three-run homer, a Ryan Theriot two-run double and a Jim Edmonds two-run single.
That eased Dempster, who varied his pitches and his speeds to baffle the Braves. His split-finger was particularly nasty.
"Today, I got it going early, and it was a really good pitch for me, whether I was getting a strikeout with it or getting a ground ball or even just changing speeds," Dempster said. "Aside from having fastball command, it was the difference-maker for me today."
Dempster worked into the ninth one other time this season, against San Diego on May 15. He didn't give up a run to the Padres, but he put two runners on and was two outs away from a complete game when manager Lou Piniella brought in Kerry Wood to save a four-run lead.
This time, Dempster shut the door. After Omar Infante reached on an error, he got Mark Teixeira to ground into a double play and struck out Ruben Gotay.
"Tonight, he was nice and fresh," Piniella said. "He wanted to finish, he deserved to finish and he did."
Working deep into games is a question mark when stretching out relief pitchers. Just ask the Yankees' Joba Chamberlain. But Dempster, who was an All-Star starting pitcher for the Marlins, believed early on that he could do it.
"It wasn't really a concern of mine [in Spring Training]," Dempster said. "I felt like I worked pretty hard this winter to go late in ballgames. I just didn't want to come back and be a five-inning pitcher."
Has Dempster reverted back to his old starting form? No, he's better than that. Dempster's lowest ERA when he was in the Florida Marlins' rotation was 3.66. It's down to 2.81 following Wednesday's performance.
"I remember him as a starter with the Marlins in those days, and he's different," Braves manager Bobby Cox said. "He's a real pitcher. He's under control and mixes [pitches] well. He looks in terrific shape."
The Cubs hitters are looking pretty good, too. With two outs in the first, Derrek Lee walked, Aramis Ramirez singled and Fukudome plated them with his fifth homer. The blast gave the rookie, who once produced 34 round-trippers in a season in Japan, three home runs in a span of 34 at-bats after having only one homer through 34 games.
Corky Miller's pinch-hit, two-run homer broke up Dempster's shutout with two outs in the seventh, but that didn't keep Piniella from praising his starter.
Every time Dempster starts, the manager is asked how the right-hander has been able to transition so effortlessly from the bullpen to the rotation. On cue, he was asked again after another Dempster "W."
"Remember, he was a starter before he went to the bullpen," Piniella said. "He's more experienced. He's pitched under the scrutiny of closing for a year and a half here. He's added some pitches. I'll tell you what, he came to camp ready to fight [boxer Oscar] De La Hoya for 15 rounds. He was in shape, and he was on a mission, and he's gotten off to a great start."