PHOENIX -- Brandon Belt believes he has not hit his stride this season, but Arizona would argue the point.
Belt's three-run home run in the eighth inning Wednesday gave the San Francisco Giants a 7-6 lead en route to a 9-6 victory over the Diamondbacks at Chase Field, his second game-deciding hit of the series and third against Arizona in the past 10 days.
"It's one of things, you just keep on trying to get better," Belt said. "You start off slow and you want to steadily make improvements. I feel like I've been doing that in hopes that I can go on a hot streak pretty soon."
Belt is hitting .239, but he has 10 hits in his last 28 at-bats, including all three of his home runs. All have come against the D-backs. On Wednesday, his game-changing blast came on an 0-2 fastball off David Hernandez (1-2).
"I threw the first two (pitches) exactly where I wanted to throw them, and the third one was right where he wanted me to throw it," said Hernandez, whose three blown saves have all come against the Giants. "Just through the last week and a half, two weeks, for me, I just haven't been able to locate very many pitches."
On Monday, Belt's two-run single broke a 4-4 tie the series opener, and his single gave the Giants a walk-off, 5-4 win when the teams met at AT&T Park on April 22.
"Obviously, he's been hot against us. We're happy to see him leave, by the way," Arizona manager Kirk Gibson said.
Pablo Sandoval hit a run-scoring double in a two-run ninth as the Giants completed a three-game sweep. Sandoval has 12 hits in his last 22 at-bats, and he set a Giants record with 35 hits in April.
"These guys have been amazing in their comebacks," Giants manager Bruce Bochy said. "Guys are coming through when we needed them."
Arizona shortstop Cliff Pennington homered, doubled and tied a career high with four RBIs. His three-run homer off Giants starter Tim Lincecum gave the D-backs a 3-1 lead in the second inning.
Lincecum gave up five runs and a career-high 10 hits in five innings, while D-backs starter Brandon McCarthy allowed four runs and eight hits in six innings. Neither factored in the decision.
Paul Goldschmidt singled in a run against Lincecum for a 5-3 lead in the fifth inning, making him 9-for-17 with 11 RBIs against the two-time Cy Young Award winner in his career. Goldschmidt has hit safely in all seven games the two have met.
San Francisco's Angel Pagan hit his sixth career leadoff homer two pitches into the game. He also doubled, and he drove in two and scored three times. Hunter Pence homered, doubled and scored twice, and Gregor Blanco had two hits and two runs.
"A few bad pitches. Overall it is encouraging. There are a few little things I can do better," said McCarthy, who was in line for his first victory of the season before the bullpen squandered the lead.
Arizona's Eric Chavez had three hits and scored twice, and A.J. Pollock had two hits and scored twice. Martin Prado had two hits and scored a run.
Giants middle reliever George Kontos (2-1) threw 1 2/3 scoreless innings. Jean Machi and Santiago Casilla combined to blank the Diamondbacks in the eighth, and Sergio Romo pitched the ninth for his 11th save, tied for the major league lead.
NOTES: Giants 2B Marco Scutaro sat out, and with Thursday's off day, he will have consecutive days off for the first time this season. "Give Marco a chance to get a nice break here. His back has flared up on him a little bit," manager Bruce Bochy said. Scutaro, who has nine hits in his last 44 plate appearances, started the previous 11 games and 25 of the first 27. ... McCarthy entered the game with a .396 batting average on balls in play (BABIP), more than 100 points higher than his career average of .288, which is also about the league average every year. ... Pennington, a switch hitter, has hit 21 of his 25 career home runs against right-handers. His last four have come against Justin Masterson, Dan Haren, Hiroki Kuroda and Lincecum.