Scott Hairston homered twice, including a leadoff shot in the 10th inning off Santiago Casilla, and the New York Mets won a wild 8-7 contest over San Francisco to send the Giants to their season- high fifth straight loss.
Pinch-Hitter Justin Turner doubled home the go-ahead tally during a four-run eighth inning, but the Giants rallied for two in the ninth for a 6-6 tie thanks to RBI doubles from Buster Posey and Nate Schierholtz.
In the 10th, Hairston struck a 1-1 curveball over the wall in left-center. Jason Bay walked with one out and Mike Baxter, just activated from the 15-day disabled list, had a pinch-hit single up the middle.
Clay Hensley was summoned from the bullpen to replace Casilla (4-5) and Rob Johnson bunted toward the mound. Hensley looked toward second before firing home late, as Bay scored standing up.
Schierholtz singled in Ryan Theriot with two outs in the bottom of the 10th, but Manny Acosta regrouped and secured his first save of the year by retiring Brandon Belt on a fly ball to the warning track in center field.
"Manny Acosta, two years in a row, has been an outstanding pitcher in the second half of the season. We need him now," Mets manager Terry Collins said.
Hairston and Bay each scored three times for the Mets, who won back-to-back contests for the first time since ending June with a four-game winning streak.
The Giants left 15 men on base and fell into a virtual first-place tie with the Dodgers in the NL West.
"It was a wild game. A lot of little things happened. We swung the bats, but made some mistakes and it came back to get us," Giants manager Bruce Bochy said.
Hairston's two-run blast to left off Sergio Romo in the eighth tied the game and Turner doubled off the base of the wall in left-center later in the frame to plate Jason Bay. Rob Johnson capped the outburst with an RBI single for a 6-4 lead, but Bobby Parnell and Josh Edgin (1-0) couldn't hold the advantage.
Posey's double to the alley in left-center plated Melky Cabrera, and later Schierholtz laced what turned out to be a double to right. Ike Davis, playing in at first base, saw the ball bounce under his glove into the outfield. With the bases full and Marco Scutaro facing a 3-2 pitch, Edgin painted the outside corner to send the game to the 10th.
Scutaro's sacrifice fly in the third gave the Giants the lead, but Ronny Cedeno doubled home two runs in the fourth.
Cabrera's single plated Scutaro in the fifth, and the Giants went ahead 4-2 in the sixth. Pinch-hitter Aubrey Huff beat out a potential double play ball to score one run, but he left the game with an apparent leg injury after running hard to first. With runners at the corners, Theriot singled to right to plate pinch-runner Matt Cain.
New York is 3-2 on its season-high 11-game road trip...The Mets came into Monday batting .184 with men in scoring position over their last 13 games, but went 3-for-8 in such situations in the opener of this four-game series...Mets center fielder Andres Torres hurt his thumb while legging out a hit in the fifth inning...Giants center fielder Angel Pagan hurt his right hand punching something after an at-bat...The Giants had a season-high 16 hits...Giants starter Madison Bumgarner had nine strikeouts over six innings, and New York's Jeremy Hefner allowed 10 hits and four runs over the first 5 2/3 frames...Edgin got his first major league win.