Rookies Dominic Smith, left, and Amed Rosario of the Mets...

Rookies Dominic Smith, left, and Amed Rosario of the Mets prepare for a game against the Yankees at Yankee Stadium on  Aug. 15, 2017. Credit: Jim McIsaac

Mets phenoms Amed Rosario and Dom Smith may be first-timers to the Subway Series. But on Tuesday night, they looked like old pros.

Smith hit a two-run shot in the seventh for the first homer of his big-league career. In the ninth, Rosario hammered a two-run homer against the fireballing closer Aroldis Chapman.

The Mets still fell, 5-4, and dropped both games in the Bronx. But Rosario and Smith showed that despite their first foray into the rivalry, they weren’t rattled by the bright lights.

“Everything is magnified,” said Smith, who was promoted Friday. “Every play could be make or break the whole game. Every game is played tight. You see the Yankees went to the bullpen pretty early, so they’re trying to win ballgames. We’ve just got to continue to grind and play well against some of the best pitchers in the game.”

Rosario has shown an early penchant for clutch situations. Since being promoted Aug. 1, both of his homers have come in the ninth, to the opposite field, against a closer.

“In that situation I’ve got to try to cut down on the pressure,” Rosario said through a translator. “I went out there looking for his hardest pitch and I hit his slowest pitch.”

At shortstop, Rosario also flashed the smooth defense and strong arm that had scouts raving in the minor leagues.

“The environment, it was very loud, it’s something that I’ve never experienced before in my life,” Rosario said. “And every day I learn a little bit more here in New York.”

Both prospects refer to each other often as brothers and grew close as they climbed the minor leagues together. On Tuesday, both seemed to relish trying to prove they are quick studies. For Rosario, that meant making an adjustment in the middle of his at-bat with Chapman. The homer came on a slider, a pitch he chased earlier in the evening. For Smith, that meant resisting the urge to test the short porch in right.

“You see 314 down the line and that’s pretty much what I was doing the first game and a half, I was pulling off pitches and rolling them over because I could see that short porch and just trying to do too much,” Smith said. “In that last at-bat, I was more patient, more calm, and like you said I went back to what got me here. I tried to take what he gave me and not do too much.”

When Sonny Gray left a 92-mph heater up and away, Smith went with the pitch, driving it to the opposite field. Rosario said he celebrated “almost as if I had hit it myself.”

“Me and Amed, we came up together,” Smith said. “He’s my little brother. We want each other to do well, root for each other, push each other to become better ballplayers. It’s good to be up here with him and it’s just a good feeling to see him play well as well.”

Against Chapman, Terry Collins pinch hit for Smith with Jose Reyes, who singled against the hard-throwing lefty. But he insisted that Smith will get his chances to keep learning.

“I think it’s great,” Collins said of the Yankee Stadium experience. “You can’t have a better scenario, I don’t think, for young player development than pressure situations. I believe that at any level. There’s a time when they need to be challenged and when they come up here, you have to challenge them with big opportunities like tonight.”

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