ST. PETERSBURG, Fla. — Entering Saturday, nothing was promised to Christian Scott, who took a major league mound for the first time without an assured second start.

It was as if the Mets’ best pitching prospect tried, with one night, to prove he could do everything.

Scott could battle.

He could sail.

He could pitch to soft contact, and he could turn to filth to generate swings that made major league hitters look amateur.

A large part of the future of the Mets took the stage and made a case to never leave it.

“Oh yeah, he’ll get another one,” manager Carlos Mendoza said of Scott, who dazzled in just about every way imaginable and earned his way to at least another turn through the rotation.

The only thing he couldn’t do was hit, his offense letting him down in a 3-1 loss to the Rays at Tropicana Field.

The Mets (16-17) never found the big hit they needed, going 1-for-10 with runners in scoring position.

They were burned by a pair of bases-loaded walks in the eighth, first by the previously excellent Adam Ottavino and then Sean Reid-Foley.

Wasted was a brilliant play from Francisco Lindor, who had gotten the inning’s second out with a force at home plate on a backhanded stab and fadeaway throw to the plate.

Mendoza’s group, which has dropped nine of 13 and is below .500 for the first time since April 14, has a questionable present but a future that suddenly looks brighter.

Pitching in front of an estimated 50 family and friends — plus a sizable portion of the 7 Line Army, which cheered him on from warm-ups to his walk off the mound — Scott first survived and then thrived.

The 24-year-old Floridian twirled 6 ²/₃ innings of one-run ball, both efficient and excellent for a rotation that has needed both.

But before he was terrific, he had to prove he was tough.

The first three batters Scott faced reached on a single, double and single that gave the Rays a run and runners on the corners before he could blink.

Just about every eye in the Mets’ organization was trained on Scott to see how he would handle the moment.

“I was just trying to see how he was reacting, and he looked so calm,” said Scott’s catcher, Tomas Nido.

“All right, let’s see what we got with him,” was going through Mendoza’s mind.

They were looking for signs of jitters.

They never found them.

On pitch 18, he reached back and threw a fastball by Randy Arozarena to record his first out.

Pitch 19 got him two outs, Harold Ramirez bouncing into a double play started and smoothly handled by Brett Baty.

Perhaps it helped Scott relax, but that would presuppose he had been tight. What has stood out about Scott — beyond his excellent stuff and command — is an ability to act cool under pressure.

“A lot of people told me I’d have trouble sleeping [Friday night],” Scott said with a smile. “I slept like a baby.”

After escaping the jam, a fired-up Scott walked off the mound, appeared to settle in and showed off the kind of stuff that has made him so tantalizing.

After those three straight reached to begin the game, Scott retired the next 12 batters he saw.

There was the three-pitch strikeout of Jose Caballero, who swung through sweepers that he couldn’t reach.

The same sweeper made Arozarena look silly, unable to hold up on strike three. Scott struck out six while allowing five hits — just two after the first — on the night.

“I know my stuff plays here,” said Scott, who induced 18 swings-and-misses, the most by a Mets pitcher this season.

He didn’t encounter trouble again until the fifth, when a fielder’s choice, a steal of second and an error brought a runner to third base in a 1-1 game.

But Scott rose with the moment, turning again to the sweeper to punch out Jose Siri.

Scott was pulled with two outs and a runner on first in the seventh inning, and the Coconut Creek native walked off the mound to a standing ovation in what qualified as a personal home game and a team road game.

Reed Garrett stranded the runner, but the Rays broke through an inning later.

The Mets’ clubhouse was quiet afterward, disappointment in a loss and in spoiling a rookie’s gem.

The night will be remembered, though, for the first 6 ²/₃ innings.

“As good as advertised,” Nido said. “He belongs.”