The Cubs (56-83) have lost 14 of their last 17 games, and entered Wednesday’s game with the league’s worst record in the NL after dropping their first two games with the Pirates (56-84).
Chicago moved out of the cellar with a 7-2 win on Wednesday, as Lee hit a grand slam on his 31st birthday.
He has homered on four straight birthdays, and has five home runs in his career on his birthday.
Lee had career highs of 46 homers, 107 RBIs and a .335 average en route to his first batting title last season. He was hitting .318 with three home runs and 10 RBIs through 14 games before breaking two bones in his right wrist in a collision on April 19.
He was activated from the disabled list for a second time on Aug. 28, and is batting .424 (14-for-33) with two homers and 10 RBIs in nine games since.
“I feel good,” Lee said. “I’m seeing the ball good. I feel like I’m hitting the ball hard more consistently now, and that’s all I try to do, is hit the ball hard.”
While Lee is surging at the plate, Cubs third baseman Aramis Ramirez has gone hitless in his last 14 at-bats. Since hitting his 31st homer on Aug. 24, the slugger has matched a season high by going 12 straight games without a home run.
Despite his recent struggles at the plate, Ramirez is batting .636 (7-for-11) with four homers, three doubles and 10 RBIs in his career against Thursday’s starter for Pittsburgh, Shawn Chacon (1-2, 6.00 ERA).
Chacon has been inconsistent in five starts since being acquired from the New York Yankees on July 31. He has allowed a total of two runs in 15 innings in two of his starts, but has given up a combined 14 runs through six innings in his two losses.
The right-hander allowed four hits and four walks in five innings of a 1-0 win over St. Louis on Saturday, but was not a factor in the decision.
“We got a very competitive five innings from Shawn Chacon,” Pittsburgh manager Jim Tracy said. “Obviously he dealt with baserunners through the first five innings that he pitched, but he made pitches when he had to, put innings down and got outs.”
Chacon is just 1-4 with a 9.27 ERA in seven career games against the Cubs.
Chicago counters with rookie Shawn Marshall (5-9, 5.05), who looks to improve upon his first start since coming off the DL.
Marshall allowed four runs and five hits—including three home runs—in 5 2-3 innings of a 4-2 loss to San Francisco on Saturday, his first start since he strained his right oblique muscle on July 22.
The left-hander is 1-0 in two career starts against Pittsburgh, allowing five runs, nine hits and two walks in 12 1-3 innings.
Pirates second baseman Jose Castillo went 2-for-3 with a double on Wednesday, and is batting .340 (18-for-53) in 18 games against the Cubs this season.