Edgar Renteria backed Todd Wellemeyer’s surprisingly solid outing by going 3-for-4 with two RBI and a run scored, as the Giants downed the Phillies, 6-2, at AT&T Park.

Wellemeyer (1-3) entered the game with an 8.16 earned-run average in three previous starts this season but held Philadelphia to two runs on three hits and three walks in seven-plus frames.

Pablo Sandoval went 2-for-4 with a pair of RBI, while Aubrey Huff and Matt Downs each had a solo homer for San Francisco, which won the opener of the three-game set, 5-1.

Jamie Moyer (2-2) allowed four runs on 10 hits in a six-inning start to take the loss, the Phillies’ fourth in five games. Ryan Howard, who on Monday signed the richest contract in franchise history, had two of the club’s five hits.

Raul Ibanez’s sacrifice fly scored Jayson Werth in the second, and the Giants countered with solo home runs from Huff and Downs in the bottom half.

Wellemeyer jump-started a rally with a one-out single in the fifth, as Andres Torres followed with a double and Renteria and Sandoval each posted run- scoring base hits.

After Wellemeyer retired his 11th straight hitter in the top of the seventh, the Giants added two more runs in the home half.

Chad Durbin relieved Moyer and opened the inning with a walk to Torres, who stole second and scored on Renteria’s line-drive single to center. Sandoval then hit a one-hopper that ate up Howard at first, allowing Renteria to come around and score from first.

Ben Francisco recorded a pinch-hit, RBI single in the away eighth to make it 6-2 before Dan Runzler fanned Shane Victorino looking and got Placido Polanco to ground into an inning-ending double play.

Brandon Medders hurled a scoreless ninth.

Game Notes

The Giants will look to complete the sweep on Wednesday with ace Tim Lincecum on the hill opposite Philadelphia’s Cole Hamels…Wellemeyer entered the game 0-2 with a 6.75 ERA in eight career games versus the Phillies, four of those starts…Moyer was 4-6 with a 3.31 ERA in 11 career starts against the Giants entering play on Tuesday…San Francisco has won eight of its last 11 versus Philadelphia.