PORT ST. LUCIE — It was only one inning consisting of 17 pitches, but Rick Porcello received a taste Saturday of competing in a Mets uniform.

Two weak singles, including a broken-bat shot by Garrett Cooper, produced a run against the veteran right-hander, who later admitted he wasn’t ready for the Marlins’ running game — Monte Harrison stole second and third base against him.

“Today was a good first step in the right direction and there is some differences from the American League game to the National League game,” Porcello said on a day the Mets lost 5-3 to the Marlins in the Grapefruit League opener at Clover Park.

“I saw it today, the running game, they don’t really steal bases that much in the American League and you get out there and first pitch with a runner on first and he’s gone. I will start paying attention to that more and be prepared for a little bit of change in the style of play, but the main focus is building that foundation with that delivery and go from there.”

Porcello, who spent 11 seasons pitching for the Tigers and Red Sox, arrived in December on a one-year contract worth $10 million. He is battling for a spot in the Mets’ rotation this spring after a career-worst season in which he posted a 5.52 ERA with the Red Sox.

Porcello had hoped pitching coach Jeremy Hefner would allow him to return for a second inning against the Marlins, but said that option wasn’t presented to him. In his inning of work, Porcello allowed a groundball single to Harrison before striking out Isan Diaz for the second out. But Harrison, following his two stolen bases, scored on Cooper’s broken-bat single.

Rick Porcello
Rick PorcelloAnthony J. Causi

“Today, that is the closest you are going to get to that feeling, when you get out there the first time in the regular season,” Porcello said. “Everyone is excited for the first game of spring. I’m excited to be out there on the mound again after a long offseason, so you work on things on the side, but you don’t have that same adrenaline going and your body tends to speed up, your mind tends to speed up, so the setting today, and it’s part of the reason I want to pitch in as many games as possible this spring and not in backfields.”

Wilson Ramos was behind the plate for Porcello and placed an emphasis on a low target for the former AL Cy Young award winner. To get that low target, Ramos set up with a knee on the ground.

“I know it’s just one inning, but [Porcello] threw the ball really well, kept the ball down, it felt good giving a low target,” Ramos said. “That’s what I’ve been working all spring, this offseason, so I feel good with that target so I have to keep doing it and try to keep those guys happy.”

Porcello, Steven Matz and Michael Wacha are likely competing for two spots in the rotation, with the third-place contestant headed to the bullpen. Matz’s first opportunity this exhibition season will come Sunday against the Cardinals.

New manager Luis Rojas gave Porcello a thumbs up on his initial Mets outing.

“It was a good inning for him, throwing the ball where he wanted,” Rojas said. “I thought he hit his spots and it looked smooth.”

And the early chemistry between Porcello and Ramos was a plus, according to Rojas.

“I like Ramos with the knee down being able to get Porcello’s fastball,” Rojas said. “Porcello’s fastball action, the two-seamer, Ramos was really good receiving it down in the zone. There were a couple of strikes early that hit the spots and Ramos was receiving it cleanly.”