The Pirates managed only one hit against Cubs starter Matt Garza, who struck out five over five scoreless innings in his season debut, but they rallied in the sixth against the Chicago bullpen. Pittsburgh loaded the bases against Hector Rondon and James Russell (1-1) walked in a run before Snider's blast to right-center off Shawn Camp.

Pittsburgh starter Wandy Rodriguez (5-2) won his third straight start, limiting the Cubs to three runs on six hits over six innings. Two relievers pitched scoreless frames to bridge the gap to Jason Grilli, who allowed a run in the ninth but struck out Anthony Rizzo to leave the tying run at third for his league-leading 18th save in as many chances.

The Cubs took a 3-0 lead in the second, when Darwin Barney singled home a run and Garza followed by slicing a double that rolled to the wall in right-center and scored Barney and Welington Castillo.

Garza, who began the season on the disabled list with a strained left lat, didn't allow a hit until Clint Barmes' line-drive single to right with two outs in the fifth in his first major-league start in 10 months.

GAME NOTEBOOK: Snider's grand slam was the first of his career and his first home run as a pinch hitter. … Cubs pitchers are 12-for-38 with two home runs and 13 RBIs this month. The 13 RBIs are the most for Cubs pitchers in a calendar month since September 1971. … Barney went 4-for-4, raising his average to .223 and finishing the day above .200 for the first time since May 1.