Steven Matz is coming home.

Mets general manager Sandy Alderson announced Friday afternoon that the long-awaited arrival of the Long Island native will come Sunday at Citi Field, when the highly touted pitching prospect makes his major league debut against the Reds.

The 24-year-old southpaw from Stony Brook had spent the entire season with Triple-A Las Vegas, posting a 7-4 record while leading the league with a 2.19 ERA and 94 strikeouts in 90 1/3 innings. He will not join the team until the weekend.

“This kid’s very, very talented,” Mets manager Terry Collins said before the Mets’ 2-1 win over the Reds. “I was there the day he showed up [at spring training] and you saw the arm and you said, ‘Wow, if he learns to command his stuff he’s gonna be outstanding.’ Well, he did.

“This kid might have so far put up the best numbers I’ve ever seen anyone pitch in that ballpark in Las Vegas. …That is a hitter’s paradise. He continued to pitch well up there and we’ll see how he does up here.”

Matz, who was selected by the Mets in the second round of the 2009 MLB Draft but missed all of the 2010 and 2011 seasons after undergoing Tommy John surgery, will not be on a strict pitch count in his debut, according to Collins, with Alderson noting the organization had been limiting his workload over the past month in preparation for his insertion into the rotation.

“He’s gonna be full out when he gets here,” Collins said. “We’re all excited to get Steven up here. The fact that he’s gonna be in the mix is very interesting. We’ve talked about how these guys compete off one another, and it’ll be interesting to see how his introduction here adds to the rotation and maybe adds some energy.”

Alderson admitted two weeks ago that Matz – who has posted a 2.29 ERA in four seasons in the minor leagues – had nothing left to prove in Las Vegas, but the Mets wanted to be certain the call-up did not come prior to the cutoff for Super-2 arbitration eligibility.

Matz’s promotion – which pushes Sunday’s scheduled starter Jon Niese to Tuesday – also means the Mets will be returning to a six-man rotation, which was inconsistently implemented earlier this month, featuring Dillon Gee.

This time, though, Alderson said, the six-man rotation will not account for off-days and will not skip starters, noting Matz’s call-up was as much about his continued excellence as about limiting the innings of the team’s multiple 20-something-year-old starters.

“In the case of two, maybe three, of our starters, we have serious concern about the overall volume,” Alderson said. “We have to be fairly strict and disciplined about this because we could get to the end of the season and some of our guys simply won’t have any capacity left in our reasonable judgment.

“This is intended to be as strict as we can make it. … Part of it will depend on performance – let’s face it – or injury. We have six now, it doesn’t mean we’ll have six at the end of the season. … It doesn’t mean it’s cast in concrete that we’re gonna do this through the end of the season, [but] this is our best shot at it.”

Alderson acknowledged the plan could change late in the season if the postseason is in play, in order to maximize the number of appearances from the team’s top starters. Collins said the rotation order could be altered during the All-Star break, in order to keep similar-style staff members from facing the same team.

Though the starters did not previously embrace the six-man rotation, each pitcher was notified of the changes and Collins believes they understand the desire to protect the young arms — and call one up.

“They’re on board,” Collins said. “It’s to benefit the whole organization, so we look up and everyone’s pitching and we’re not pushing guys back and we’re not skipping guys. They’re out there and competing and that’s what they want to do.

“We don’t have a crystal ball. There’s no indication it’s going to fail, either. We just think it’s in the best interest of everybody to give this a legitimate chance.”

Noah Syndergaard agreed, saying it’s worth using if it means all the starters will still be pitching at the end of the year:

“It’s just an extra day of recovery. I think it’s going to be an easy adaptation. … The ultimate goal is to be able pitch in October, and part of November as well, so if the starting rotation is able to pitch in October and November it’s gonna be a force to deal with.”