SAN FRANCISCO -- The San Francisco Giants have spent a majority of the season trying to figure out where their luck and Jeff Samardzija's skill have gone.

When both things came together Wednesday afternoon, they regained their winning formula.

Pittsburgh Pirates left fielder Starling Marte misplayed Brandon Belt's fly ball with two outs in the bottom of the seventh inning, allowing Miguel Gomez to score the go-ahead run and send the Giants to a 2-1 victory.

"It's nice to get a break like that," San Francisco manager Bruce Bochy said. "And we get the run in in time to get Shark the win, too."

Samardzija, whose name has been mentioned in trade rumors, pitched seven strong innings for his second win over the Pirates this month.

The Giants took two of three from the National League Central contender, who arrived in San Francisco having won six of its last eight games.

"It was an excellent pitched game all the way around," Pirates manager Clint Hurdle said. "What can you do (about the mishap in left field)? It happens."

Pinch-hitting for Samardzija in a 1-1 game, Gomez led off the seventh with a double against Pirates reliever Tony Watson (5-3).

After Denard Span bunted Gomez to third and Joe Panik grounded out, Belt went the opposite way with a deep fly to left field.

Marte, playing deep, had trouble tracking the ball. He did a 360 as he drifted back, and then had the ball fall at his feet, allowing Gomez to score the eventual winning run.

The hit was called a double.

"I heard the sound of the ball off the bat and knew it was hit well," Marte said. "I saw the ball and the wind started to knock it down. The sun made it hard, so I took my eyes off the ball, but I saw it at the end."

Hunter Strickland got Andrew McCutchen to line into a double play to escape the eighth inning unscathed, and Giants closer Sam Dyson pitched a 1-2-3 ninth for his sixth straight save.

Samardzija (5-11), who began the day tied for the second-most losses in the majors, both pitched and fielded brilliantly.

After allowing the Pirates' only run on an Adam Frazier double in the second inning, Samardzija intentionally walked Jordy Mercer to load the bases with one out.

Pirates starting pitcher Trevor Williams then hit a chopper between the mound and third base, a ball the 6-foot-5 Samardzija jumped to corral with his bare hand. His off-balance throw to the plate barely beat Francisco Cervelli for the second out.

"It was the only option I had," the former football star at Notre Dame said. "Cervelli's running at third. I thought as long as I didn't throw it to the backstop, we'd be OK."

Samardzija then got Marte to pop up to end the inning.

Later, pitching in a 1-1 tie in the seventh and Frazier on second, Samardzija snared a hard one-hopper by pinch-hitter David Freese that appeared headed to center field. The out at first base ended the inning.

"He's an athlete," Bochy said. "That play up the middle, for a pitcher, it's one of the better plays I've seen."

Samardzija allowed one run and four hits in his seven innings. He walked two and struck out eight.

"At one time, he was the best wide receiver in Chicago and that might include the pro team," Hurdle said of Samardzija. "It doesn't surprise me when he makes a play like that."

Williams matched his counterpart pitch-for-pitch for six innings, giving up only one run and five hits. He walked three and struck out two.

The Giants' only run off Williams came in the first inning on a bases-loaded fielder's choice by Brandon Crawford, scoring Panik, who had doubled.

Gorkys Hernandez had two hits for the Giants, who had lost seven in a row at home to the Pirates before winning the last two of the series.

Buster Posey reached base four straight times, three times on walks, two intentional.

Frazier and Josh Harrison had two hits apiece for the Pirates, who continue a nine-game trip Friday in San Diego.

The Giants out-hit the Pirates 7-5.

NOTES: Before the game, the Giants promoted OF Carlos Moncrief from Triple-A Sacramento to take the roster spot created when 3B Eduardo Nunez was traded Tuesday night to the Boston Red Sox. ... Giants general manager Bobby Evans announced before the game that RHP Shaun Anderson, acquired in the Nunez trade, would begin his Giants career at Class A San Jose. ... Left-handed-hitting 3B Conor Gillaspie started in Nunez's place Wednesday, but Giants manager Bruce Bochy noted he would be looking for a righty option when his club faces three left-handed starters against the Los Angeles Dodgers later this week. No, he said, recently signed 3B Pablo Sandoval, a switch hitter currently playing at Triple-A Sacramento, was not an option. ... Giants RHP Johnny Cueto (blisters) threw a 45-pitch bullpen session before the game and could return to the starting rotation as early as Monday at Oakland. ... Pirates manager Clint Hurdle disclosed before the game that his club, with RF Gregory Polanco (strained hamstring) on the disabled list, remains interested in adding a fourth outfielder before the trade deadline.