SAN FRANCISCO (AP) — Pablo Sandoval hit a two-run home run in the bottom of the 10th inning after Gregor Blanco’s tying triple in the ninth, and the San Francisco Giants rallied past the Washington Nationals 4-2 on Tuesday night.

Sandoval flipped his bat and shifted into a slow trot as soon as he sent the ball off Yunesky Maya (0-1) over the right-center field wall for his eighth homer this season. It was Sandoval’s second career game-ending hit — both home runs against the Nationals — and San Francisco’s sixth walk-off win this season.

Blanco had three hits, including his RBI triple off closer Rafael Soriano with two outs in the ninth. The Giants’ comeback upstaged a superb outing by Stephen Strasburg, who outdueled Matt Cain in seven innings in a matchup of NL aces.

Jeremy Affelft (1-0) pitched a scoreless inning for the win.

Maya had been called up from Triple-A Syracuse earlier in the day after the Nationals placed reliever Ryan Mattheus on the 15-day disabled lis. Mattheus broke his right pitching hand punching a locker following a loss at San Diego on Sunday.

The Giants earned their 13th comeback win this season. After entering the game just 2-17 when trailing after the eighth inning, they handed Soriano his second straight blown third in in 15 chances this year.

Buster Posey hit an infield single leading the ninth against Soriano and was lifted for pinch-runner Andres Torres. With San Francisco down to its last strike, Blanco sent an 84 mph slider over the head of right fielder Bryce Harper for a tying triple.

What started out as a superb matchup of NL aces faded at the finish.

Strasburg struck out seven in seven innings, allowing five hits and three walks. Cain gave up four hits and two walks while striking out seven in seven innings.

Strasburg had his changeup confusing hitters most of the night. He retired 14 of the final 15 batters — six on strikeouts — and never allowed a runner past first in his last five innings.

Ian Desmond and Ryan Zimmerman each hit an RBI double in the first to give the Nationals a 2-0 lead. Blanco singled, stole second and hustled home to score on Angel Pagan’s single in the second for San Francisco’s only run off Strasburg.

Cain worked out of a bases-loaded jam in the fourth. He got Kurt Suzuki to ground into a fielder’s choice and Strasburg struck out swinging after an appeal to first base umpire Gary Darling.

Neither starter faced a serious threat the rest of the way.

Span doubled off lefty Javier Lopez leading off the eighth and reached second on Harper’s second sacrifice bunt of the game. Lopez struck out Adam LaRoche, and Jean Machi got Desmond to ground out and give San Francisco a strong to rally.

Marco Scutaro extended his hitting streak to 19 games — the longest in the majors this season — when he doubled off the left-field wall against Tyler Clippard with two outs in the eighth. Pablo Sandoval followed with a weak grounder to second to end the inning.

NOTES: Sandoval’s other game-ending hit came on May 12, 2009 at Washington. ... Several Nationals players wore a T-shirt in the clubhouse that had a younger image of pitching coach Steve McCatty shirtless from when he posed for Playgirl magazine’s July 1984 issue after the photo recently surfaced on the Internet. The back of the shirt had the slogan: “Untuck.” ‘’I could have done without that revelation,” manager Davey Johnson joked. “I didn’t know he had that good a body, and I didn’t know he had that much hair.” ... Giants manager Bruce Bochy said Johnson will be on his coaching staff for the NL All-Star team. “He’s all set to go. I have tremendous respect for Davey,” Bochy said. ... Madison Bumgarner (4-2, 3.09 ERA) will start for the Giants opposite Washington’s Gio Gonzalez (3-2, 4.01 ERA) in a matchup of hard-throwing young lefties in Wednesday’s series finale.