CHICAGO -- Derrek Lee took a curtain call after his second homer, a grand slam that gave him a career-high seven RBI on a night when the baseball seemed to be coming at a different speed.

"Just some nights the game seems like it slows down a little bit and tonight was one of those nights," Lee said after leading the Chicago Cubs to a 9-5 win over the Milwaukee Brewers in the opener of an 11-game homestand.

The Cubs also got homers from Geovany Soto and Jake Fox as their erratic offense showed some spark against Brewers starter Seth McClung and reliever Chris Smith.

"It makes it fun to hit when everyone is swinging the bats well. There are guys on base and pressure on the pitcher," Lee said. "Tonight is a great night, but we're right back here tomorrow at 1. ... So, turn the page."

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Lee drove his 10th career grand slam off Smith in the fourth after connecting for a three-run shot off McClung in the first. Fox and Soto also had solo shots off McClung (3-2), who was making just his second start of the season.

The Brewers entered the game with a one-game lead over the Cardinals in the NL Central, but are now only a percentage point ahead after St. Louis beat the Giants.

McClung gave up seven hits and seven earned runs in 3 1/3 innings.

"It is disappointing to know that I got an opportunity to show what I could do," said McClung, who's been primarily a reliever.

"It's disheartening. I know I'm better than the statistics I put up the last couple of times."

Ryan Dempster (5-5) got his first win since May 30 and improved his career record against the Brewers to 10-3. He gave up four runs -- three earned -- and eight hits in 6 2/3 innings, including Mike Cameron's 13th homer in the second and Prince Fielder's 21st in the sixth.

He left after Ryan Braun's RBI single in the seventh, and Jason Kendall's RBI single off Aaron Heilman cut the Chicago lead to 9-5 in the eighth.

"Our offense gave us a chance, our starting pitching didn't," Brewers manager Ken Macha said. "You've got to locate the ball to Lee and we didn't do it."

Sam Fuld, replacing slumping Alfonso Soriano, drew a leadoff walk in the first, Ryan Theriot singled and Lee sent his 13th homer deep into the left field bleachers. One out later, Fox hit his third home run of the season to give Dempster an early 4-0 cushion.

"This is an important series," Cubs manager Lou Piniella said. "Derrek has been swinging the bat well now for awhile. You look up there and all of a sudden you see 14 home runs and 48 RBI and around a .290 (.285) batting average. He's getting some runs in for us, which is important."

After Cameron's two-run drive cut the lead in half, the Cubs drove out McClung with a five-run fourth.

Soto led off with his eighth homer. After a single by Mike Fontenot, a sacrifice and infield single by Fuld, Smith relieved and walked Theriot to load the bases for Lee, who sent another long drive into the left-field bleachers.

"Bases loaded and a 3-1 count is about the best situation you can be in," Lee said. "He has to throw a strike. He can't walk you there, so I tried to be aggressive."

"I'm just swinging the bat well right now," he added. "I'm getting a pitch to hit and putting a swing on it."

Notes

• It was Milwaukee's first trip to Wrigley Field this season, even though the teams are in the same division and located only 90 miles apart.
• Cubs 3B Aramis Ramirez (shoulder) and CF Reed Johnson (back) will begin rehab assignments with Class A Peoria this weekend. Ramirez is slated to play three games beginning Friday and Johnson will start Saturday. Both could be activated by the Cubs on Monday.