They'll see if he can get his bat going right away, but James McDonald may have something to say about that.Roughly 24 hours after being acquired, Pence is expected to make his debut with the Phillies as they try to end McDonald's unbeaten run and continue their home dominance of the Pittsburgh Pirates on Saturday night.Philadelphia (66-39) owns the best record in the majors, and is in position for a fifth consecutive NL East title despite a mediocre .249 team average. In an effort to improve offensively, the Phillies acquired Pence from Houston on Friday in exchange for a package of highly rated prospects.Pence, a two-time All-Star, was the Astros' best hitter, leading them with a .308 average, 11 homers and 62 RBIs.He's slated to start in right field Saturday and should bat fifth, adding protection behind former MVP Ryan Howard. The move also means Domonic Brown, one of the Phillies' highly regarded youngsters, may be headed for the bench or the minors."We tried to address a need that we felt was a missing piece," general manager Ruben Amaro Jr. said. "This gives us a little more balance."Despite offensive struggles for much of the season, Philadelphia scored eight times in the opening two innings Friday and collected 11 hits with two homers in a 10-3 rout of the Pirates (54-50) to open this three-game set.The Phillies have won 12 of 14 against Pittsburgh at Citizens Bank Park.Pence is batting .444 with four homers and 20 RBIs in his last 26 games versus the Pirates, and is 5 for 8 against McDonald.McDonald (7-4, 3.95 ERA), however, is 4-0 with a 2.54 ERA in his last eight starts, and has tossed 11 2/3 scoreless innings while fanning 16 and winning his last two. He won four games all of last year.The right-hander was impressive again Monday, striking out a career-high nine in 5 1/3 innings of a 3-1 victory at Atlanta."The confidence is pretty high, but I still can't get content with what I'm doing," McDonald told the Pirates' website. "There is still a lot of work to be done. I still have a lot of season left in front of me."McDonald's most recent loss came against the Phillies on June 5. He lasted four-plus innings, allowing three runs with five walks and a hit batsman in a 7-3 defeat.The Phillies will counter with Cliff Lee (9-7, 3.05), who is looking to win for the first time since beating Boston on June 28.The left-hander is 0-2 with a 4.97 ERA in four starts this month, getting tagged for at least five runs and 10 hits twice. He had gone 5-0 in June, yielding one run in 42 innings.Lee's recent struggles continued Monday, when he surrendered five runs and 10 hits in four innings of a 5-4 loss to San Diego. One run scored when Chris Denorfia stole home in the second inning on a pickoff attempt to first base."That's the first time that's ever happened," Lee said. "I didn't even consider that as a possibility right there. Next time I'm in that situation, I need to make a more firm throw to first and not allow that to happen."He'll face Pittsburgh for just the second time. He didn't get a decision after allowing two runs in seven innings of Cleveland's 3-2 loss June 25, 2009.