Because he's pitching Sunday night, Adam Wainwright likely won't play in the All-Star game. That start, though, gives the St. Louis Cardinals right-hander the chance to end the first half as the NL's only 13-game winner.While seeking that victory and his first against the Chicago Cubs in nearly three years, Wainwright will also try to help St. Louis regain sole possession of the NL Central lead before the break.The Cardinals (56-36) changed their pitching schedule to give Wainwright two starts before the end of the first half, but starting Sunday will at least limit him in Tuesday's Midsummer Classic at New York's Citi Field. The latest collective bargaining agreement gives pitchers who start on Sunday the option of throwing in the All-Star game but no more than one inning.Wainwright (12-5, 2.30 ERA) has said he would ideally like to give his spot to Cardinals closer Edward Mujica. Should he choose to opt out, however, the choice of his replacement would fall to San Francisco manager Bruce Bochy."I don't think you can make a (final) decision on it until we see what happens (Sunday)," Wainwright told the team's website. "I mean, if the game were to get rained out and I backed out for no reason that would be silly. But if I pitch (Sunday), then I would probably forgo the chance to pitch in the All-Star game to allow for some rest."First, Wainwright will try to break a tie with Washington's Jordan Zimmermann for the NL wins lead. He matched Zimmermann's victory total by allowing one run over seven innings and striking out nine in a 9-5 victory against Houston on Tuesday.Since undergoing Tommy John surgery in 2011, Wainwright is 0-2 with a 5.90 ERA in five starts against the Cubs (42-50). He gave up four runs over seven innings in his only matchup this season, a 4-2 loss June 18.Wainwright's last win against Chicago was on Sept. 24, 2010, and Travis Wood (6-6, 2.69) will try to help prevent him from earning another.Wood, the Cubs' lone All-Star, faces the same decision as Wainwright."It's going to be a (side session day) anyway. I've got no problem with him pitching one inning, or 20 pitches. He goes all out on his side days anyways," manager Dale Sveum told the team's website.In his final start of the first half, Wood will try to build on his first win since May 30. The left-hander gave up two runs over 6 23 innings in a 7-2 victory over the Los Angeles Angels on Tuesday. He got six runs of support after receiving a combined nine in his previous six outings.Wood has split his two starts against the Cardinals this season. He gave up one run over 6 23 innings in a 2-1 victory at Wrigley Field on May 7, and allowed four runs in seven innings in a 5-2 road loss June 17.St. Louis will try to hand him another defeat while attempting to move back in front of Pittsburgh in the NL Central.The Cubs are trying to end the first half with a 12th win in 18 games.Chicago also has a chance to win the four-game series over its archrivals after claiming a 6-4 victory Saturday. Alfonso Soriano hit his ninth homer in 15 games, and Luis Valbuena had a key two-run shot in the fourth inning.Neither Matt Holliday (hamstring) nor All-Star catcher Yadier Molina (right knee) were in the starting lineup Saturday, although Molina entered in the eighth inning.