FORT MYERS, Fla. -- Watching Pete Alonso launch a baseball over the Green Monster at Fenway South on Saturday, it was easy to imagine the 24-year-old doing similar damage at big-league ballparks around the country.

The first baseman has done nothing but impress this spring, but the question remains: when March 28 rolls around, will Alonso be on the Opening Day roster?

Alonso’s home run highlighted a 10-2 Mets win over the Red Sox at JetBlue Park on Saturday, part of a 2-for-4 day that raised his average to .423 this spring.

“I’m happy with all the hard work and preparation coming together,” Alonso said. “Having tangible success in games, that’s really huge. It’s a big confidence booster. I’m really happy with how I’m playing right now. I’m just going to keep on continuing to prepare the best I can for each day and see what happens. Just go out there and compete the best I can.”

He’s doing just that, making life difficult for manager Mickey Callaway and general manager Brodie Van Wagenen, who must decide whether to take Alonso or Dominic Smith on the roster, though Todd Frazier’s oblique strain could open the door for both to make the club.

“We won’t be hesitant to take the 25 best guys,” Callaway said. “If we feel like we’re covered on the left side and we feel like both of those guys could contribute at first base, we wouldn’t hesitate to do that.”

Pitchers may hesitate when it comes to throwing anything in the zone to Alonso, who demolished Tyler Thornburg’s first-pitch fastball to start the sixth inning Saturday, sending it soaring over Florida’s version of the famed Green Monster.

“I haven’t seen too many home runs where nobody on the field moved,” Brandon Nimmo said. “That was pretty impressive. Literally no one moved. The only people that moved were people’s heads on top of the wall.”

“We know he can hit it out of any park,” Callaway said. “That was really high and really far.”

Alonso’s fiancée, Haley, is from the Boston area, giving the young slugger great joy as he knew his future in-laws were watching the game.

“That was pretty cool to do it for them,” Alonso said. “That’s for the Local 12 Association -- that’s my father-in-law’s union. That was for those guys.”

Alonso hasn’t necessarily been surprised by his production this spring, citing his preparation both on and off the field for his approach at the plate. He routinely studies opposing pitchers, their tendencies, strengths and weaknesses to create a blueprint for each game. Having led the Minor Leagues with 36 homers last year, Alonso has seemingly picked up this spring right where he left off.

“It’s really cool to see my plan work in a game,” said Alonso, who now has three home runs and a team-high 23 total bases this spring. “Baseball is a funny game sometimes; you can have the right plan and the results don’t come in the games. Right now, I think it’s really cool that things are coming together.”

Although Alonso’s bat is what helped him become the Mets’ No. 1 prospect, according to MLB Pipeline, Callaway has been equally impressed by his defensive prowess at first base.

“When you talk about Alonso, you talk about offense; but I knew the offense was going to be somewhat special,” Callaway said. “For me, the defense and how locked into a game he is every day, at first base you have to be locked in on every situation. All the little things that it takes to be a quality Major League player, he’s doing them on defense. That’s probably been the most surprising thing.”

Alonso isn’t obsessing with his place on the Mets or whether he’ll be with them in Washington on Opening Day. He knows Smith (.435/.500/.609) is also having a superb spring, and although that could potentially mean a trip back to Syracuse to open the season, Alonso isn’t rooting against his teammate.

“Me and Dom, we played together last year and spent some good time together, I’m really happy he’s playing well this spring,” Alonso said. “I just put blinders on. We talk in the clubhouse, like, ‘Hey, how’d you do?’ It’s a friendly thing. I want everyone to do well. I don’t want anyone to not succeed. I want every one of my teammates to out and play the best they can, because ultimately that helps the team win.”