SAN FRANCISCO -- Marlon Byrd's seventh career grand slam might have enhanced his trade value.
At the very least, it assured manager Terry Collins that his 35-year-old slugger still has something left to offer.
"Marlon's been unbelievable, he really has,'' Collins said. "[He] just goes up and does what he does. He's an attack guy and if you make a mistake he can do some damage. That's what happened.''
A day after needing 16 innings to top the Giants in a game that ended at 12:42 a.m., the Mets squandered leads of 3-2 and 5-3 but held off the slumping World Series champs by scoring five times against the Giants bullpen.
Omar Quintanilla singled off reliever Jose Mijares (0-2) with one out in the eighth and took second on pinch-hitter Juan Lagares' single against Jeremy Affeldt. Both runners moved up on a wild pitch and Eric Young Jr. walked before Daniel Murphy's sacrifice fly drove in Quintanilla with the tiebreaking run. After Wright walked to load the bases, Byrd hit his 14th home run on a hanging slider from Dunning to give the Mets a cushion.
"I knew they weren't really going to pitch to David, so whoever's hitting behind him at some point you have to come through,'' Byrd said. "It was nice to come through there. I've had seven good swings with the bases loaded but I've also had some strikeouts.''
Quintanilla had three hits for the Mets while Byrd and David Wright added two apiece. Wright drew a two-out walk before Byrd's home run.
Marco Scutaro singled twice for the Giants but was thrown out at home trying to score from first base on Pablo Sandoval's double in the first.
The Giants scored more than four runs for just the fourth time in 22 games but still lost and fell a season-high nine games under .500. San Francisco also has the worst record in the majors (17-34) since May 13.
"It seems like all the hard work is spitting in our face,'' said Affeldt, who recorded just one out and allowed three runs. "We don't know what else to do but work hard, but it doesn't seem to be getting us anywhere. All around we stink, to be honest with you. I really stink.''
Scott Rice (4-5) retired one batter for the win as the Mets overcame a shaky outing by starter Dillon Gee. Gee allowed five runs and nine hits over 6 2-3 innings. He also walked five.
Carlos Torres pitched the final two innings and gave up Nick Noonan's pinch-hit RBI single in the ninth, one night after New York's bullpen tossed nine scoreless innings.
San Francisco's bullpen was also stellar in the extra-inning game on Monday but couldn't follow suit this time after the Giants scored single runs in three straight innings to tie the game at 5-all.
"We had a chance to put that game away earlier and we didn't do it,'' Collins said. "So (Byrd's) hit was huge for us.''
Both clubs were still showing the effects from Monday's game.
Bochy scrapped batting practice and told his players they didn't have to report until two hours before first pitch. Bochy kept All-Star catcher Buster Posey out of the starting lineup after Posey caught all 16 innings in the 4-3 loss.
The Mets rested catcher John Buck, who also went the distance a night earlier.
Buck's replacement, Anthony Recker, committed an error in the second inning that allowed Hunter Pence to score San Francisco's first run. Pence reached on an infield hit leading off and took third on Brandon Belt's single before Recker threw wildly into center trying to catch Belt on an attempted steal.
The Giants went up 2-0 later in the inning but the Mets scored three times in the fourth to take the lead. Quintanilla's two-out base hit drove in Josh Satin to put New York ahead.
After Sandoval's run-scoring groundout in the fifth tied it at 3, Recker connected off San Francisco starter Barry Zito in the sixth to put the Mets ahead 5-3.
The Giants scored once in the sixth then tied it again on Sandoval's sacrifice fly in the seventh.
San Francisco got a lift from rookie Kensuke Tanaka, who was called up from the minors before the game. Tanaka singled, walked and scored and made a leaping catch at the wall to rob Andrew Brown of a potential home run in the second.
Zito remained winless in his last seven starts dating to May 30. ... David Wright has a 10-game hitting streak. ... Mets RHP Shaun Marcum will have season-ending surgery on his pitching shoulder Monday in St. Louis. Marcum experienced tingling and numbness in his right hand Saturday night against Milwaukee. Torres will replace Marcum in the rotation, and RHP Gonzalez Germen was called up from Triple-A Las Vegas. ... San Francisco placed backup catcher Hector Sanchez on the 15-day disabled list with a strained right shoulder. Pitcher Michael Kickham was called up from Triple-A Fresno and designated OF Cole Gillespie for assignment. ... Veteran OF Jeff Francoeur agreed to terms on a minor league contract with San Francisco. ... RHP Matt Cain (5-5) faces former Giants prospect Zack Wheeler (2-1) in the series finale. Wheeler was the Giants first-round pick in 2009 when he was the sixth player taken overall.