Jordy Mercer added three hits and scored a run and Starling Marte was 2-for-4 with an RBI for the Pirates. Brandon Cumpton (2-2) allowed two runs and five hits over five innings for his second straight win and the Pittsburgh bullpen worked four hitless innings with Jason Grilli earning his 10th save with a perfect ninth.

Luis Valbuena had three of the Cubs' five hits and John Baker and Darwin Barney each drove in a run. Starter Jason Hammel (6-4) allowed a season-high 11 hits and four runs over five innings to absorb the loss.

McCutchen's two-run blast in the first marked the first runs allowed by Hammel since May 25, and snapped his streak of 51 2/3 innings without surrendering a homer. The Cubs answered in the second, scoring on Baker's RBI single up the middle and Barney's run-scoring groundout to tie it.

Gregory Polanco's first career RBI on a groundout put Pittsburgh ahead for good in the bottom of the inning, and Marte singled home a run in the third to make it 4-2. The Cubs loaded the bases in the fifth before Cumpton struck out Nate Schierholtz to end the threat, and Chicago managed only one baserunner over the final four innings.

GAME NOTEBOOK: The start of the game was delayed 1 hour, 38 minutes because of rain. … McCutchen also had a three-game homer streak from April 21-23. … Pirates 2B Josh Harrison left in the third inning because of pain in his left ankle.