Alfonso Soriano hit a two-run homer in the eighth inning to give the Cubs the go-ahead runs and Chicago completed a three-game sweep of the Pittsburgh Pirates with a 4-2 win on Sunday.
Soriano followed Anthony Rizzo's leadoff single in the eighth with his second homer in as many days and 28th of the season, sending the first pitch from Jason Grilli (1-6) into the Cubs bullpen in left-center.
Josh Vitters and Anthony Recker each hit solo home runs for the Cubs in the fourth.
Andrew McCutchen homered and Brock Holt had three hits for the Pirates.
James Russell (7-1) earned the win for Chicago.