NEW YORK -- Noah Syndergaard and Madison Bumgarner were nowhere to be found Monday night, when the New York Mets and San Francisco Giants met for the first time since two of baseball's best pitchers matched zeros in last October's National League wild-card game.

Fortunately for the Mets, Michael Conforto, Wilmer Flores and Neil Walker -- none of whom played in the wild-card game -- were easy to find in the ninth inning.

Walker's two-out single scored Conforto in the ninth and capped a piecemeal rally as the Mets edged the Giants 4-3.

"Guys are taking advantage of opportunities, and that's a really important thing at this level," Walker said following the third walk-off hit of his career.

Conforto hit just .220 last season and was not on the roster when Syndergaard threw seven innings of two-hit ball and Bumgarner threw a four-hit complete game in the Giants' 3-0 win on Oct. 5.

However, Conforto continued his breakout season Monday when he led off the ninth by working a five-pitch walk against Josh Osich (0-1). It was the third time in five plate appearances Conforto reached base. He is batting .325 with 19 runs this season, including .333 with 17 runs in 16 starts out of the leadoff spot.

Two outs later, Flores, who didn't play after Sept. 10 last year due to a right wrist injury, singled off the leg of Giants right-hander Hunter Strickland. It was just the fourth hit for Flores in 33 at-bats against right-handers this year.

Walker, who took in the wild-card game from the dugout after undergoing back surgery in September, fouled off three straight pitches against Strickland before lacing a shot down the right field line. Conforto scored easily as Walker was mobbed by teammates in between first and second base.

"Flo's getting some more at-bats, even against righties -- that's a huge hit there in the ninth inning," Walker said of Flores. "Guys like Michael Conforto, you know that he's a superstar in the making, so to watch him (get) on base is fun. We need every single one of these guys to get where we need to go."

Walker's hit allowed Jeurys Familia -- who took the loss in the wild-card game after giving up a three-run homer in the ninth inning to Conor Gillaspie -- to earn the win. Familia (1-0) threw just five pitches in a perfect ninth on Monday.

"He certainly remembers it," Mets manager Terry Collins said of Familia. "There's no question. To be able to get out there against them is important for him. I hope we get a chance in the postseason to do it again."

By that point, both Syndergaard (out three months with a torn right lat) and Bumgarner (out at least two months with shoulder and rib injuries sustained during a dirt bike accident) should be back, though their teams have plenty of work to do to create a rematch in October.

While the Mets (15-16) have won seven of 10 to avoid falling into a big early-season hole, the Giants (11-22) have the worst record in the National League after losing four straight and seven of 10. San Francisco is already seven games out in the wild-card race and 9 1/2 games out in the NL West.

"Yeah, shoot, it's tough," said Giants catcher Buster Posey, who homered in the sixth inning. "Trying to do everything you can to get a win and just coming up a little bit short."

Walker also had an RBI double in the first inning and finished 2-for-5. T.J. Rivera delivered a game-tying RBI double in the fifth, and Curtis Granderson tied the game again with a pinch-hit, run-scoring double in the sixth.

Flores and Rene Rivera each had two hits for the Mets, who stranded nine runners -- all in scoring position -- in the first eight innings.

"Guys did a great job of getting out of some jams, but it caught up with us," Giants manager Bruce Bochy said.

Hunter Pence hit a two-run homer in the first for the Giants. Posey and Joe Panik both had two hits.

Mets right-hander Jacob deGrom gave up three runs on four hits and three walks while striking out 11 over six innings. Giants left-hander Matt Moore allowed three runs on seven hits and one walk while striking out five over 5 1/3 innings.

NOTES: The Mets added LHP Tommy Milone, whom they claimed off waivers from the Milwaukee Brewers on Sunday, to their 25-man roster and designated LHP Adam Wilk for assignment. Milone threw a bullpen Monday and is expected to start for the Mets on Wednesday in the series finale. ... Giants SS Brandon Crawford (right groin strain) went 1-for-3 with a double in a rehab game for Double-A Richmond. It may be the only rehab appearance for Crawford, who could be activated as early as Tuesday.