Recap: Arizona vs. San Francisco

Phoenix, AZ (Sports Network) - Brandon Belt clubbed a go-ahead, three-run homer in the top of the eighth inning to help the San Francisco Giants complete a three-game sweep of the Arizona Diamondbacks with a 9-6 victory on Wednesday at Chase Field.

Arizona reliever David Hernandez (1-2) started the eighth on the hill and issued a one-out free pass to Hunter Pence before walking Gregor Blanco with two outs.

"That was the worst part of it all was two walks," said Arizona manager Kirk Gibson on the bullpen blowing the game. "We walked four guys in two innings and they all scored."

Belt, who smacked a two-out, two-run single in the eighth inning of Monday's series opener to lift the Giants to victory, then jumped on an 0-2 fastball and launched it over the wall down the right-field line to put the visitors in front.

"It's just one of those things, you just keep trying to get better, you start off slow, you want to steadily make improvements," said Belt. "I feel like I've been doing that and hope I can go on a streak here, pretty soon."

George Kontos (2-1) earned the victory after spinning 1 2/3 scoreless innings in relief, while Sergio Romo worked around a one-out single in the ninth to nail down his 11th save of the season.

Angel Pagan went 2-for-4 with a solo homer, two RBI and three runs scored, while Pence added a solo shot and two runs scored for the Giants, who wrapped up a six-game road trip at 3-3.

Arizona, which held a one-run lead in the ninth inning Tuesday before Pablo Sandoval scorched a go-ahead, two-run homer, received a solid effort from starter Brandon McCarthy, who scattered eight hits and struck out six over six innings of work.

Cliff Pennington belted a three-run homer and finished with four RBI, while Eric Chavez collected three hits, two runs scored and an RBI in the setback, Arizona's first in a series-finale this season (8-1).

After Belt's blast put the Giants in front, Jean Machi and Santiago Casilla combined to blank the Diamondbacks in the bottom half before San Francisco added a pair of runs in the ninth to give Romo some breathing room.

Pagan and Brandon Crawford walked to start the frame before Sandoval doubled to center to score Pagan. Buster Posey added a sacrifice fly to account for the final margin.

Pagan pounded McCarthy's second pitch of the game over the right-field wall, but Pennington's three-run shot in the second gave Arizona a 3-1 lead.

Chavez clubbed a run-scoring double in the fourth to add to Arizona's lead, but Pagan's RBI double preceded Crawford's run-scoring triple in the fifth to bring the Giants within one.

Paul Goldschmidt answered with an RBI single in the bottom half to restore the home team's two-run lead before Pence's one-out solo shot in the sixth trimmed the margin in half.

Pennington plated another run in the bottom half with a one-out double to left to again put the Diamondbacks ahead by two, but Belt erased the deficit with one swing of the bat in the eighth to give the Giants the lead for good.