WASHINGTON -- The first time J.D. Martinez heard “OMG,” the Jose Iglesias earworm that has become a summer anthem for the Mets, he urged Iglesias to play it for the rest of the clubhouse. The rest has become the stuff of modern Mets legend. Iglesias’ teammates took to the song, blaring it after wins. Mets marketing types got on board as well, making “OMG” a regular feature following home runs at Citi Field. It all culminated in a postgame concert last Friday at Citi Field.

While Martinez, for obvious reasons, hasn’t received the same publicity as Iglesias, his role in helping promote the song is telling. Since arriving in New York at the end of April, Martinez has done so much for other players in the clubhouse -- for Iglesias, for Pete Alonso, for Brandon Nimmo and others -- that his personal contributions can sometimes fade to the background.

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Just not on Monday. With his team at risk of suffering a difficult loss at Nationals Park, Martinez hit a go-ahead three-run homer to key a six-run 10th inning in a 9-7 win over the Nats.

“And honestly, I thought he was a little off today,” manager Carlos Mendoza said. “That tells you all you need to know how good of a hitter [he is].”

Stuck in an 0-for-12 funk as he approached the plate in the 10th, Martinez clubbed a Hunter Harvey pitch a projected 420 feet onto the batter’s eye in straightaway center field. The Mets later tacked on key runs thanks to Francisco Alvarez, who hit an RBI triple, and Iglesias, who homered to nearly the same spot as Martinez.

Despite his recent struggles, Martinez is still batting .278/.360/.493 with 10 home runs in 56 games. And yet it’s possible that his greatest contributions have come in the batting cage and the clubhouse, where he’s helped several of his teammates thrive. Multiple Mets have referred to Martinez as a third hitting coach, given his expertise in that area.

While Martinez may not be able to add "voice coach" to his resume as well, he’s at least a decent hype guy. Asked if he might deliver his own postgame concert at Citi Field someday, Martinez laughed.

“Oh, no, we’re not doing any more of those,” he said. “We helped [Iglesias] out. We gave him everything he needed. It’s on him now.”

TRIPLE TROLL

Unlike many at Nationals Park, Alvarez didn’t know right away that his 10th-inning liner would stay in the yard. That’s why he sprinted out of the batter’s box, hoping for extra bases.

It wound up being his first career triple, which Mendoza cited as evidence of the 22-year-old catcher’s work ethic. Upon sliding headfirst into third base, Alvarez looked up at the visiting dugout, his helmet partially obscuring his face -- but not enough to hide his wide grin.

“I enjoyed that triple a lot,” he said, laughing.

Alvarez also had a two-run double in the sixth and finished with three RBIs. Despite ranking in just the 18th percentile of Statcast’s sprint speed metric, Alvarez has three stolen bases to go along with his triple in 161 career games.

“That’s who he is, man,” Mendoza said. “This is a kid that’s always playing really hard with a lot of energy, and you saw the emotions there when he got to third base.”

SHAKY RELIEF

The less uplifting part of New York’s win came at the very end. After the Mets scored six times in the top of the 10th, relievers Tyler Jay and Reed Garrett allowed four of their own in the bottom of the inning, putting the tying runs on base before Garrett finally struck out Luis García Jr. to end things.

Since June 24, when Edwin Díaz was suspended for a sticky stuff violation, Mets relievers have produced a 7.20 ERA, with Garrett, Dedniel Núñez, Matt Festa and Danny Young among those asked to contribute in unfamiliar, high-leverage roles. On Monday, Garrett warmed up twice before entering, as Mendoza tried to straddle the line between resting one of his top available relievers and ensuring the victory.

“We’ve been running this guy pretty hard,” Mendoza said.

How long can this continue? Multiple industry sources said on Monday that the Mets have been in contact with rival clubs about acquiring relief pitching, perhaps with an eye toward jumping the market a month before the Trade Deadline. But no deal has occurred, and no guarantees exist that one will.

Díaz is due back on Friday, but others, such as injured relievers Brooks Raley and Drew Smith, won’t return this season. It’s created a challenging puzzle for Mendoza to piece together.