SAN FRANCISCO -- With a chance to break open a close game and possibly end a losing streak, Philadelphia Phillies manager Pete Mackanin called upon his "secret weapon" on Saturday night.

At this rate, Ty Kelly won't be a secret much longer.

Kelly capped a seven-run sixth inning with a pinch-hit grand slam, helping the Phillies rally to a 12-9 victory over the San Francisco Giants.

Rhys Hoskins had a three-run home run and Cameron Rupp a solo shot for the Phillies, who snapped a five-game losing streak and won for the first time in the four-game series after suffering losses Thursday and Friday.

"It wasn't pretty, but a win's a win and we'll take it," Mackanin insisted afterward. "I don't look happy, but I really am happy."

Denard Span drove in three runs, the first with a leadoff inside-the-park homer in the first inning, for the Giants, who lost to the Phillies at home for just the second time in their last 11 meetings.

"When you give up a three-run homer and a grand slam, that's tough to overcome," Giants manager Bruce Bochy noted. "We just unraveled there in the sixth. A couple of pitches just killed us."

The Phillies trailed 1-0 and 3-1 before entering the difference-making sixth in a 4-4 tie.

Cameron Perkins gave the Phillies the lead for good with a one-out single off Giants left-hander Ty Blach, ending his night.

Pedro Florimon and Freddy Galvis added to the lead with RBI hits off lefty Josh Osich, who then walked Nick Williams and Hoskins to load the bases with two outs.

Right-hander Cory Gearrin came on to face Kelly, who pulled the third pitch over the right-field wall for his second home run of the season and first career grand slam, pushing the Phillies' lead to 11-4.

"Pretty amazing," gushed Kelly, who had been a homerless 5-for-35 (.143) previously in his career as a pinch hitter. "Down and in is where lefties like it. The game's changing; maybe that's not the case anymore. But that's the way I grew up."

The four RBIs gave Kelly 14 with just 14 hits this season.

"You just have to take advantage of the opportunities you're given," the former New York Met said. "I've been fortunate to get a lot of great opportunities. Bases loaded ... you can't get a much greater opportunity than that."

Kelly was batting for just the second time in six games on the Phillies' Western swing.

"He's my secret weapon," Mackanin insisted. "One thing he does: He doesn't over-swing. If you make a mistake, like they did tonight, he doesn't try to over-swing. He just drops the head (of the bat) on it."

Blach (8-9), who had pitched at least six innings in each of his previous eight starts, was charged with six runs in 5 1/3 innings. He gave up eight hits and two walks, and struck out three.

"I left the ball over the middle of the plate in a hitter's count and he put a good swing on it," Blach said of Kelly's slam. "I wasn't as crisp as I have been."

Left-hander Adam Morgan (1-1), who retired the only batter he faced in relief of starter Jerad Eickhoff in the fifth inning, got the win.

Galvis had three hits and Rupp two for the Phillies, who began the night hitting just .225 against left-handed starters, the lowest in the majors.

Sandoval collected two hits and two RBIs, and Span had two hits for the Giants, who out-hit the Phillies 14-13.

Six of the Giants' hits came in a five-run rally in the bottom of the ninth that closed the gap to 12-9.

Phillies closer Hector Neris came on to record the final out, striking out Carlos Moncrief as the potential tying run, to earn his 14th save.

Sandoval had a two-run single in the uprising.

"It was fun to watch," Bochy said of the ninth. "There was a lot of energy in the dugout and the fans were getting into it. You love the fight. We get the tying run up after being down 12-4. That's something."

Span's inside-the-park home run came on Eickhoff's first pitch of the game. The ball caromed off the wall in right-center field and eluded right fielder Perkins, who reached down but inadvertently kicked the ball away.

Span was generously awarded a home run, his ninth of the season.

Span's two-run single in the second inning gave the Giants a 3-1 lead, before Hoskins' three-run shot in the third put the Phillies on top for the first time at 4-3.

Eickhoff was pulled two outs into the fifth inning of a 4-4 game, having allowed four runs and eight hits in 4 2/3 innings. He walked two and struck out three.

NOTES: INF/OF Ty Kelly's pinch-hit grand slam was just the second in the majors this season. Cleveland Indians 3B/OF Lonnie Chisenhall had one against the Detroit Tigers on April 14. ... The seven runs scored by the Phillies in the sixth inning equaled their second-most in any inning this season. They had a 12-run first against the Washington Nationals on April 8. ... The inside-the-park home run by Giants CF Denard Span was the 11th in the 18-year history of AT&T Park and the second this month. Chicago Cubs INF Javier Baez had one against the Giants on Aug. 7. ... Before Span, the last Giant to lead off the first inning with an inside-the-park homer was CF Johnny Rucker against the Boston Braves at the Polo Grounds in New York on June 20, 1945. ... The game was played on the 60th anniversary of the day the New York Giants Board of Directors voted 9-1 in favor of moving to San Francisco.