PORT ST. LUCIE, Fla. -- The Mets’ Opening Day starter will be a pitcher with all of four career starts to his name.

Right-hander Clay Holmes will start March 27 in Houston, Mets manager Carlos Mendoza announced Friday, coronating a career reliever who has spent the past few months stretching out as a starter. It will be Holmes’ first rotation assignment since 2018, when he started four games as a rookie for the Pirates.

“It’s crazy what can happen in a year,” Holmes said.

Twelve months ago, Holmes was the Yankees’ closer, a longtime reliever who hadn’t started a game in more than half a decade. But Holmes privately held on to his belief that he could thrive in a rotation, and the Mets, seeking pitching this winter, agreed. They signed the 31-year-old to a three-year, $38 million contract with an opt-out after 2026, viewing Holmes as potentially the latest in a growing line of Major League relievers who have successfully transitioned to starting rotations.

Still, even Holmes didn’t arrive in Florida thinking the Mets might tab him for an Opening Day start. But as camp developed, the Mets saw their options dwindle. Sean Manaea, their best starter from a year ago, is recovering from a right oblique strain and won’t be ready for Opening Day. Kodai Senga remains on a slow progression after missing most of last season due to shoulder, triceps and calf issues; he also won’t be ready for Game 1. That left Holmes and David Peterson as the most established options in New York’s rotation.

“We’ve had guys go down early in camp,” Mendoza said. “And then seeing Clay taking that next step … not only the results -- which, I don’t know if you can put too much on the results in Spring Training -- but the characteristics on his pitches, the metrics, how he’s feeling, the workload, and things like that. He’s in a good place. We’re going to need people to step up, and he’s doing that right now.”

Senga will start one of the Mets’ first five games, though perhaps not during the opening series. Right now, Tylor Megill is lined up directly behind Holmes in the spring rotation, which would put him on track to pitch Game 2 against the Astros. But Megill has yet to actually win a spot in the Opening Day rotation.

Holmes, Senga and Peterson are all guaranteed jobs if healthy, while Megill, Griffin Canning and Paul Blackburn are still competing. The Mets intend to proceed with a five-man rotation on Opening Day, then -- if everyone is healthy -- transition to six later in the season, according to a person with knowledge of those plans.

As for Holmes, Mendoza and pitching coach Jeremy Hefner broke the news to him Thursday in the Clover Park manager’s office. Holmes accepted the assignment with his typical brand of stoicism.

“I’m not a super emotional guy,” said Holmes, who has tossed 9 2/3 scoreless innings over three starts this spring, with 13 strikeouts and four walks. “I wasn’t doing jumping jacks. But I’m excited. I don’t always show it. It wasn’t a goal coming into this, like, ‘Man, I want to be the Opening Day starter.’ But to have a little bit of … reward for the work I’ve had to put in, it feels good.”

Over the past three years with the Yankees, Holmes enjoyed stretches as one of MLB’s top closers, saving 74 games with a 2.85 ERA from 2022-24. This spring, he reported to camp prepared to stretch out to three innings in his first Grapefruit League start -- more than most pitchers throw at such an early juncture. He tossed 67 pitches in his most recent start and, with two more spring outings still on his schedule, should be good for 90-plus on March 27.

Holmes’ lack of experience may be unusual for an Opening Day starter, but it’s not unprecedented. He joins Garrett Crochet, who last year with the White Sox became the ninth modern pitcher to make his starting debut on Opening Day.

“It’s been a crazy few months, you know?” Holmes said. “But I think it’s just a testament to the work I’ve put in, but the people I’ve been around here in the organization. There was a plan in place from the get-go. I believed in it. They believed in me. There’s been a lot of work these past few months. This is just a step. It’s an honor to be out there for the first game.”