San Diego, CA (SportsNetwork.com) - Will Nieves hit a grand slam to help the San Diego Padres to a 6-4 win over the San Francisco Giants in the finale of a four-game set on Sunday.

Will Venable hit a solo home run and Alexi Amarista added an RBI triple for the Padres, who won the final three of the set after dropping the opener. Tyson Ross (1-0) allowed three runs on five hits while walking four and striking out eight in six frames.

"The guys picked me up today," Ross said. "It was a great win for the team."

Buster Posey hit a solo home run while Brandon Belt, Gregor Blanco and Matt Duffy each drove in a run for the Giants, who also got two hits and a run scored from Nori Aoki. Jake Peavy (0-1) allowed four runs on four hits with three walks and five strikeouts in four innings of work.

San Francisco went on top in the second on an RBI single from Duffy, and made it a 2-0 game in the third thanks to a run-scoring single from Belt.

San Diego went on top on a swing of the bat in the fourth, though, as Nieves hit a two-out grand slam for a 4-2 lead.

"I made a bad pitch to Nieves obviously and I can't let that happen," Peavy said.

The Giants got one back in the sixth on Blanco's RBI triple, but Amarista answered with an RBI triple of his own in the Padres sixth to make it a 5-3 game.

Posey and Venable exchanged solo homers in the seventh to keep it a two-run game.

Craig Kimbrel worked a 1-2-3 ninth for his second save of the season.

Game Notes

Aoki extended his hitting streak to 15 games, which dates back to last season ... San Diego left fielder Justin Upton went 1-for-2 with two walks and two runs scored ... San Diego hosts Arizona for three games starting on Monday ... San Francisco has its home opener on Monday when it welcomes Colorado for three games.