PORT ST. LUCIE, Fla. -- On a sunny Saturday afternoon at Clover Park, the Mets’ fifth starter competition officially began.

Tylor Megill, whose importance has only increased since Kodai Senga suffered a shoulder strain earlier this week, struck out three batters over two innings of a 10-5 loss to the Cardinals in the Mets’ Grapefruit League opener. Following a rough first inning in which he hit a batter, threw a wild pitch and allowed a run, Megill settled down during a much more efficient second.

Through it all, Megill tried to balance his dual goals of working on his repertoire and competing against Joey Lucchesi, José Butto and Max Kranick for a slot in the Mets’ Opening Day rotation.

“Obviously, I’m still trying to be competitive and not give up runs,” Megill said.

Megill threw just two split-fingered fastballs, which is a pitch he picked up late last season and now considers an important part of his repertoire. Of greater concern to the right-hander is his ability to throw first-pitch strikes with his fastball and cutter, allowing for “leverage” counts in which he can deploy his best put-away pitch.

Before coming to camp, Megill stretched out to three innings at home in Phoenix, in hopes of avoiding the wall that can affect many pitchers as they begin digging into heavier workloads. That could serve Megill well in his competition with Lucchesi, Butto and Kranick. Butto and Kranick will start the Mets’ next two games on Sunday and Monday.

Purple rain
Saturday’s most impressive pitching performance came courtesy of Nate Lavender, a left-handed reliever who gained plenty of experience “backing up” big league camp last year. In that role, Lavender frequently came over from the Minor League side to serve as pitching insurance when the Mets needed extra arms. Then-manager Buck Showalter took such a liking to Lavender that he wound up appearing in five games.

• What Lavender learned from backing up at Major League camp

Now in Major League camp on a full-time basis, Lavender profiles as the type of prospect who could help the Mets early and often this season. He showcased that ability by striking out the side on 14 pitches (11 strikes) in the eighth inning against the Cardinals.

“He’s got that fastball that it seems like hitters are having a hard time picking it up,” manager Carlos Mendoza said, explaining how Lavender has been effective despite topping out in the low 90s. “Yeah, there were shadows there, but still. I’ve been hearing about this kid for a while now. He’s got deception, and he attacks the strike zone.”

One other notable element of Lavender’s game is his hesitation move, which he deploys on occasion during his windup to throw off hitters’ timing. It’s something Lavender began experimenting with during games of catch in recent years and subsequently brought into games.

“I was like, ‘Hey, if Nestor Cortes can do it, why can’t I sort of incorporate something in there?’” Lavender said, referring to the Yankees pitcher. “I think it just found its way into my outings, and I’ve had some success with it.”

Put it all together, and it’s an intriguing package for a future bullpen arm. As a 24-year-old with Minor League options, Lavender is at a built-in disadvantage when it comes to making the team, simply because carrying him on Opening Day would force the Mets to designate one of their more experienced relievers for assignment. But regardless of whether he breaks camp with the Mets, Lavender figures to play a role for them this season.

“Definitely, we’re looking at him pretty closely,” Mendoza said. “This is a name that came up during the offseason, and here he is in a good position.”

Fujinami delayed
Reliever Shintaro Fujinami traveled back to Japan this weekend to deal with a personal issue. The Mets do not have a timeline for his return, but given the difficulties of travel to and from Asia, they expect his absence to linger for at least the better part of a week.

The hope is that Fujinami, who was not a full participant in the first two weeks of camp due to a visa issue, will be able to resolve that while he’s home. Assuming he returns to Florida by early March, Fujinami should have ample time to ramp up for Opening Day.

“Especially as a reliever, it’s not like we’ve got to get his pitch count up to 60 pitches,” Mendoza said. “I think it’s important that he gets his work in, but he’ll have plenty of time.”

New face, who dis?
Managing his first game for the Mets on Saturday, Mendoza sported a goatee, which he was not allowed to have during his years as a Yankees coach. Early reviews on the facial hair have been positive.

“My wife likes it,” Mendoza said, laughing. “So that’s a good thing.”