Mets' Pete Alonso celebrates after hitting a three-run home run...

Mets' Pete Alonso celebrates after hitting a three-run home run during the ninth inning of a baseball game against the Miami Marlins, Monday, April 1, 2019, in Miami. It was Alonso's first major league home run.  Credit: AP/Brynn Anderson

MIAMI — As two dozen teammates loitered by the bathroom at the opposite end of the clubhouse, waiting to celebrate Pete Alonso’s first career home run and the Mets’ 7-3 win over the Marlins on Monday night, the rookie slugger first had to address laundry concerns.

He took off his cleats, then his hat, then his jersey. He wasn’t sure what was about to happen, but he figured it would be messy.

Alonso ran across the room to the hooting and hollering Mets, hopped into a laundry cart way too small for his 6-3, 245-pound frame and triumphantly raised one finger in the air as he was wheeled into the showers at Marlins Park.

Instead of water, teammates doused him with anything they could find — beer, for sure, but also barbecue sauce, shaving cream, mayonnaise and even a couple of eggs.

That is not an uncommon way for a big-league team to honor an individual achievement — first homer, first win, no-hitter — but for Alonso, it was new.

“My eyes were stinging, like, really bad,” he said. “I kept my mouth closed the entire time.”

Alonso’s blast was huge in the literal and the figurative sense. It came with two on and one out in the ninth and the Mets holding a one-run lead courtesy of Amed Rosario’s opposite-field single.

Drew Steckenrider’s first-pitch fastball over the middle of the plate landed 444 feet from home, well beyond the centerfield wall, and came off Alonso’s bat at 112.8 mph. By the time Alonso returned to his locker, the baseball was resting on a shelf, ready for safekeeping.

He said he’ll put it with his first-hit ball from last week, “and that’s in a secret location.”

“We knew that was going to come at some point, so it’s not a surprise, but it’s still a special occasion for a young player,” manager Mickey Callaway said. “And speaking of young players, look who did all the work in that inning.”

Pinch hitter Dominic Smith started the rally with an opposite-field single. Juan Lagares, who of his own volition tried to get a two-strike bunt down, ended up on first base when plate umpire Sam Holbrook ruled that his foul bunt actually was a hit-by-pitch off his right index finger (X-rays were negative). That call infuriated Marlins manager Don Mattingly, who told reporters: “It was a rough night for [THE UMPS]. The league needs to look at it.”

Brandon Nimmo struck out, but Rosario put the Mets ahead and Alonso provided the exclamation point. After he got back to the dugout, Callaway told him his night was over and that Smith, a stronger defensive first baseman, would relieve him.

A fired-up Alonso chest-bumped Smith in the dugout and yelled: “Lock this down now! Lock this down! Get a ‘W’!”

Edwin Diaz loaded the bases with none out in the bottom of the ninth, bringing the tying run to the plate, but he struck out the next three batters to end it.

The ninth-inning excitement turned everything else into a footnote. Steven Matz pitched well in his season debut, allowing three runs (one earned) in 5 1⁄3 innings. Lagares homered in the seventh to tie it. Tim Peterson tossed 1 2⁄3 scoreless innings. J.D. Davis made several questionable plays at third. Smith, who has come off the bench to play a key role in three late-inning rallies in four games, will start at first Tuesday, Callaway said.

It was Alonso & Co. who came through when it mattered most.

“Those are our youngest players,” Callaway said. “There’s excitement here, and it should be for a long time. It’s pretty neat.”

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