Marte and Jordy Mercer each had three hits for the Pirates, who had 15 in all.
The game marked the first return to PNC Park for former Pirates star outfielder Andrew McCutchen, prompting several ovations and video tributes. McCutchen, who was traded to San Francisco in January, was 1-for-5, with his one-out double in the seventh extending his streak of getting on base to 21 games but not figuring in the scoring.
"A little weird," said McCutchen pregame of entering the visitor's clubhouse. "I felt like I needed a few more steps."
The Giants lost their fifth game in a row.
Both teams got into their bullpens fairly quickly and used a combined 13 pitchers. The Pirates' seven pitchers combined for 14 strikeouts.
Pittsburgh starter Jameson Taillon was forced from the game because of a right finger laceration after giving up one hit and striking out five in three scoreless innings.
Steven Brault (3-1), who replaced Taillon, gave up two runs and two hits in the fourth but picked up the win.
San Francisco rookie starter Andrew Suarez (1-2) allowed five runs and seven hits in four innings.
The Pirates opened a 2-0 lead in the first on Marte's two-run homer, his sixth, after Gregory Polanco doubled.
The Giants tied it in the fourth against Brault on Austin Jackson's two-out, two run single.
Pittsburgh went ahead for good in the fourth. Mercer's triple brought home Sean Rodriguez, who reached on a single, for a 3-2 Pittsburgh lead. Osuna smacked a 420-foot, pinch-hit homer, his second, to extend the lead to 5-2.
In the sixth, Colin Moran's pinch-hit RBI double off the wall in center made it 6-2 after Mercer's two-out single.
Bell hit a 432-foot homer, his third, for two more runs in the seventh and an 8-2 lead.
McCutchen got another shot in the eighth, but with the bases loaded and two outs he bounced into a forceout.
Moroff added a three-run homer, his second, in the eighth to make it 11-2.
--Field Level Media
San Francisco | Pittsburgh | |
Andrew Suarez | Player | Jameson Taillon |
Loss | W/L | No Decision |
4.0 | IP | 3.0 |
5 | Strikeouts | 5 |
7 | Hits | 1 |
11.25 | ERA | 0.00 |
San Francisco | Pittsburgh | |
Gregor Blanco | Player | Jordy Mercer |
2 | Hits | 3 |
0 | RBI | 1 |
0 | HR | 0 |
2 | TB | 5 |
.500 | Avg | .750 |
Team | Hits | HR | TB | Avg | LOB | K | RBI | BB | SB | Errors |
San Francisco | 9 | 0 | 11 | .250 | 31 | 14 | 2 | 4 | 1 | 0 |
Pittsburgh | 15 | 4 | 32 | .417 | 6 | 9 | 11 | 3 | 0 | 2 |