Realmuto hit a two-run homer as Miami notched their sixth win in seven games, downing the New York Mets 3-1 in their series opener to move within two games of .500 for the first time since May 3.
"J.T.'s a tough kid. Nothing scares him. Nothing bothers him," Marlins manager Don Mattingly said. "He's taken a little bit of a step forward within our club. To me that shows some leadership and something that guys look up to because I think they know who he is."
Realmuto followed Marcell Ozuna's second-inning walk with his 14th home run, lining a hanging curveball into the left field seats to give the Marlins a 2-0 lead and prompting a raucous ovation from his mother and several other family members and friends seated in the upper deck.
"My mom's having her 60th birthday party here," Realmuto said. "So there's like 20 women up there, here partying in New York City."
Dee Gordon and some teammates looked toward the stands as Realmuto rounded the bases, pointing and cheering in the direction of the Miami catcher's relatives.
"They were loud," Realmuto added. "You could hear them everywhere."
Pitching in front of a sparse crowd in a game that started almost two hours late due to steady rain and the occasional burst of lightning, Justin Nicolino (2-1) scattered six singles and stranded runners in four of his five innings pitched.
"It's a little nerve-wracking cause on days that you start you're always routine-oriented," Nicolino said of the delayed start. "Everything's so timed, time managed, and it was a little tough at first but then once we started getting an idea of when we were playing it was like another ballgame."
Rookie Chris Flexen (2-2) worked 5 1/3 innings, allowing three runs, five hits and four walks.
The Mets have lost five straight, dropping four to the crosstown rival Yankees earlier in the week, and are 14 games below the .500 mark for the first time since the season's final day in 2013.
"When you're coming off a series that's as electrically charged as it was the last four days, even though we didn't win games, the energy in the ballpark was tremendous," Mets manager Terry Collins said. "The air might have been out of the building today a little bit. That's my responsibility to make sure they get back and be ready for tomorrow."
Four Miami relievers combined on four scoreless innings including closer Brad Ziegler, who hurled a perfect ninth for his fifth save in seven chances.
"They have great arms. All of them," Collins said. "They have power stuff and Ziegler is no fun for anybody at the end."
Ozuna's sacrifice fly in the third inning made the score 3-0.
After sitting out the last two games with a sore ribcage, Wilmer Flores drove in New York's lone run with a third-inning single.
Marlins: 1B Justin Bour (strained right oblique) will commence baseball activity next week. The burly slugger has been on the disabled list since July 25. ... LHP Wei-Yin Chen (left arm fatigue) threw a two-inning simulated game on Friday. He has not pitched since May 1. ... LHP Jarlin Garcia (strained left biceps) is scheduled to throw a bullpen session on Saturday. ... LHP Chris O'Grady (strained right oblique) will not resume baseball activity until he is pain free, said Marlins spokesman Matt Roebuck. ... 3B Martin Prado (strained right knee) is advancing with his therapy and will continue motion and strengthening exercises. ... SS JT Riddle (left shoulder tendinitis) has begun post-operation therapy following season-ending surgery last Friday. ... RHP Edinson Volquez (Tommy John surgery) also began range of motion therapy. ... RHP Nick Wittgren (strained right elbow) is improving but has not resumed activity.
Mets: RHP Jeurys Familia (blood clot in right arm) will continue his rehab assignment as he recovers from May surgery. "We want to get his pitch count to where he certainly can be comfortable throwing 30 pitches in an inning," Collins said. "So I think there's going to be a time where he's got to go at least two innings in a rehab someplace." ... RHP Matt Harvey (stress injury in right shoulder) will make at least one more start in the minors before being activated, according to Collins.
Marlins: RHP Vance Worley (2-2, 4.97 ERA) has made four starts since rejoining the rotation on July 28 and the club has won each outing, despite Worley lasting only four innings twice.
Mets: RHP Rafael Montero (1-8, 5.80 ERA) did not factor in the decision Monday night at Yankee Stadium, allowing two runs and five hits over six effective innings. The 26-year-old has no record with a 4.15 ERA in 10 appearances (three starts) against Miami, whom he has faced more than any other team.
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