SAN FRANCISCO (AP) -- With All-Star catcher Buster Posey getting a break after logging nearly five hours behind the plate a day earlier, San Francisco Giants manager Bruce Bochy knew he would have to lean heavily on Nick Hundley.
With one swing in the 12th inning, Hundley provided the Giants with far more than they expected from the veteran backup.
Hundley singled in Kelby Tomlinson with two outs in the 12th, lifting San Francisco to a 5-4 victory over the San Diego Padres on Saturday.
It was Hundley's fifth game-ending hit of his career and his first since July 11, 2014, with Baltimore. It came after Kevin Quackenbush tried to fool him with back-to-back curveballs.
"The first one was a little too far away for me to do anything with," Hundley said. "I tried to get something a little closer and thankfully I did."
One day after the teams played 11 innings in a game that lasted nearly 5 hours, the Giants and Padres had another extended battle.
Pinch-hitter Tomlinson reached on a fielder's choice and took second on a wild pitch from Quackenbush (0-2). After Hunter Pence flied out, Hundley lined an 0-1 pitch over the head of left fielder Jose Pirela as Tomlinson rounded third and scored without a throw.
It was the Giants' second win in the last nine games against their division rivals at AT&T Park.
"There were two tired teams out there," Bochy said. "When you lose a game the way we did last night and you have a day game the next day, you have some tired guys out there. And a lot of times the team that gets ahead, the other team has a tendency to get a little flat. I'm just proud how they bounced back."
Eduardo Nunez had three hits and two RBIs, Hundley singled twice and San Francisco took advantage of an error by San Diego shortstop Allen Cordoba that led to three unearned runs.
Will Myers hit his second homer in two days as part of San Diego's four-run fourth but the Padres wasted multiple opportunities and lost for the fourth time in six games.
"He hits some balls really well to the pull side," Padres manager Andy Green said. "When Wil's really rolling he's using the entire baseball field. He'll tell you the same thing. I still think there's room for growth too."
Josh Osich (3-1) retired five batters and struck out three in getting the win.
The Giants left the bases loaded in the sixth and stranded runners at second and third in the eighth.
San Diego got the go-ahead runner to third with two outs in the ninth but came up short when pinch-hitter Hector Sanchez grounded out.
Both teams had the leadoff runner on in the 10th but failed to score.
Padres starter Luis Perdomo hit his third triple of the season in the fourth inning. The last pitcher to hit three triples in a season was Dontrelle Willis in 2007. Perdomo's three triples this season are the most-ever by a Padre pitcher in team history (since 1969). The Padres have four triples in the first three games of this series. "He can fly," Green said. "I'd venture to say there's not a pitcher in the game that runs much better than he does."
Third baseman Pablo Sandoval signed a minor league contract with the Giants, returning to the team he broke into the majors with. The 2012 World Series MVP was to report to Single-A San Jose and will join Triple-A Sacramento on Tuesday. The Boston Red Sox released Sandoval on Wednesday when the third baseman didn't report after being designated for assignment last week.
Padres: INF Erick Aybar was placed on the 10-day disabled list with a bruised left foot. The injury happened Friday night when Aybar fouled a ball off his foot. LHP Buddy Bauman was reinstated from the 60-day DL to take Aybar's spot.
Giants: Posey was held out of the starting lineup after catching all 11 innings of Friday's game. San Francisco's All-Star struck out as a pinch-hitter in the ninth.
RHP Dinelson Lamet (3-4, 6.40 ERA) pitches the series finale for San Diego on Sunday while the Giants counter with LHP Ty Blach (6-5, 4.36 ERA). Lamet has had seven or more strikeouts in five of his nine starts this season.