CHICAGO — Derrek Lee refused to take his birthday off.

Turning down Cubs manager Dusty Baker's offer to rest, Lee hit a grand slam on his 31st birthday, leading the Chicago Cubs over the Pittsburgh Pirates 7-2 Wednesday night.

Lee has homered on four straight birthdays and has five home runs in his career on his birthday.

"He wasn't going to play today, but he kind of pleaded with us that he always hits home runs on his birthday, so I guess I have to listen to him. That was a big one," Baker said.

Chicago trailed 2-1 in the eighth against John Grabow (4-2) when pinch-hitter Angel Pagan, Juan Pierre and Ryan Theriot loaded the based with singles.

With one out, Lee connected off Matt Capps for his seventh career slam, his first since Aug. 24, 2004, against Milwaukee. Henry Blanco and Angel Pagan added RBI singles in the six-run inning.

Lee can't understand why he has so much success on his birthday.

"It's just a fluke, there is nothing," Lee said.

Michael Wuertz (2-1) got two outs in the eighth to win in relief of Rich Hill, who struck out 11 in 7 1-3 innings. Hill set a team record for strikeouts by a left-hander, topping Steve Wilson's 10 on July 15, 1990, against the Los Angeles Dodgers.

Chicago passed Pittsburgh and moved out of last place in the NL Central, ending its five-game losing streak to the Pirates.

Pirates starter Zach Duke allowed one unearned run and six hits in seven innings.

"Our guy was terrific," Pirates manager Jim Tracy said. "It was one of his better games of the year. He had it all working."

Ronny Paulino's passed ball allowed Ronny Cedeno to score from third base in the third.

Pittsburgh rallied for a 2-1 lead in the eighth. Hill threw wildly on pinch-hitter Jack Wilson's bunt single for a run-scoring error and the Pirates got another run on an RBI grounder to shortstop by Jose Bautista in which Cedeno threw wildly to the plate for another error.