MIAMI — The Mets looked every bit like a team missing half of its regulars as they stumbled through a sloppy afternoon Saturday.

Wilmer Flores bobbled a double-play grounder. Kevin Plawecki botched an easy force when his foot slipped off the plate. In the dugout, manager Terry Collins found himself in the middle of a triage unit, his roster crumbling under the weight of even more injuries.

Nevertheless, the Mets found themselves exchanging handshakes after an improbable 6-4 victory over the Marlins. It came because the 25th man on the roster delivered the go-ahead hit.

Pressed into action because Juan Lagares injured his thumb while making what turned out to be a game-saving catch, utilityman Matt Reynolds came off the bench in the eighth inning and stroked a pinch-hit RBI single to put the Mets ahead for good at 4-3. The hit drove in Michael Conforto, who was in the game only because Yoenis Cespedes was scratched with a sore hip 30 minutes before first pitch.

“We have a lot of guys hurt,” Reynolds said. “But we’re still a very good team that can win some ballgames.”

Alejandro De Aza had a two-run double in the ninth to give the Mets a 6-3 lead in a game in which they needed every available body. Collins cleared the bench, save for backup catcher Rene Rivera. Even pitcher Jacob deGrom was summoned for a late pinch-hitting appearance.

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But somehow the Mets made it work. For the second time in as many days, an army of fill-ins led the charge. They enter Sunday’s series finale already assured of a series victory to begin their 10-game road trip.

“We’ve got to pick each other up,” Collins said. “And guys did that today.”

In the ninth, shortstop Asdrubal Cabrera grimaced after checking his swing. He felt his forearm tighten, prompting the trainer to check on him. It proved to be a false alarm, a fortunate break on a day in which just enough went right for the Mets. Indeed, with David Wright, Travis d’Arnaud and Lucas Duda already on the shelf, they’ll need every break.

Since Wright officially went on the disabled list, Flores has responded to inheriting the starting job at third base by reaching base seven times in nine plate appearances. He finished 3-for-4 Saturday.

Bartolo Colon held the Marlins to two runs (one earned) in five innings. After an implosion by Hansel Robles, setup man Addison Reed and closer Jeurys Familia restored order — although Christian Yelich had a two-out RBI single in the ninth — to preserve one of the Mets’ unlikeliest wins of the season.

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With the bases loaded in the sixth inning, the slumping Conforto tied the score at 2-2 with a sacrifice fly.

In the bottom of the inning, Robles, in relief of Colon, issued a pair of walks with two outs and gave the Marlins the lead when Miguel Rojas lined an RBI double to left. Robles has given up seven runs in his last four appearances. Only Lagares’ sprawling catch kept the fire from spreading.

In the eighth, Conforto delivered an RBI single off David Phelps that snapped an 0-for-20 skid and tied it at 3-3. With two down, Reynolds came off the bench and singled to knock in Conforto with the go-ahead run after Marlins manager Don Mattingly elected to intentionally walk Curtis Granderson.

For the first time this season, the Mets rallied to win after trailing through seven innings. They had been 0-for-18.

Said Conforto: “To be able to grind it out was huge.”