SAN DIEGO — Chris Denorfia hit a go-ahead RBI single in the seventh inning to lift the San Diego Padres to a 3-2 victory over the Giants on Tuesday night.
Nick Hundley drew a leadoff walk in the seventh from rookie reliever Jake Dunning, who was called up earlier in the day from Triple-A Fresno. Ronnie Cedeno followed with a single to send Hundley to third and bring on reliever Javier Lopez.
Denorfia lined a 1-2 pitch to left for the single that broke a 2-2 tie.
Dunning (0-2), who made his major-league debut in June, took the loss. Tim Stauffer (3-1) got the win with 1²⁄³ innings of shutout ball.
Huston Street pitched the ninth for his 26th save in 27 chances.
Defending World Series champion San Francisco (61-77) dropped into last place in the NL West, one game behind San Diego.
San Francisco catcher Buster Posey was pinch-hit for in the seventh after he appeared to hurt his right hand on a wild pitch thrown by Madison Bumgarner in the sixth inning.
Posey shook his right hand after Bumgarner's pitch in the dirt and spent a couple of minutes being attended to by a trainer before he stayed in the game and completed the inning.
Giants center fielder Angel Pagan had a single, double and triple heading into his final at-bat in the ninth when he struck out.
San Diego took a 2-0 lead in the fifth following a leadoff double by Kyle Blanks and Hundley's one-out double. After Cedeno was walked intentionally, rookie pitcher Robbie Erlin drove in the second run with a bloop single.
Giants reliever Heath Hembree made his major-league debut with one inning of perfect relief.
Padres rookie RHP Burch Smith will start on Friday against Colorado. Smith, who was recalled from Triple-A Tucson on Monday, is 0-1 with an 18.41 ERA in three starts earlier this season with San Diego . Giants RHP Tim Lincecum (8-13, 4.38 ERA) opposes Padres LHP Eric Stults (8-12, 3.81) in the series finale Wednesday.