Soto finished 3-for-5 with two doubles, a homer and three runs scored for the Cubs, who are 12-3 over their last 15 games. Derrek Lee drove in two runs and Alfonso Soriano had three hits and scored twice in the win.

Chicago leads the majors with 82 wins and is five games ahead of the Milwaukee Brewers for first place in the National League Central.

Cubs starter Carlos Zambrano lasted only 4 1/3 innings after allowing six runs on eight hits. The win went to Sean Marshall (3-3), who pitched a scoreless seventh.

Adam LaRoche, Doug Mientkiewicz and Jack Wilson each drove in two runs for Pittsburgh, which has lost six straight and 10 of its last 12. Nyjer Morgan was 3-for-5 with an RBI in the loss.