MLB

J.D. Martinez has two-hit night in his Mets’ debut: ‘be competitive’

J.D. Martinez took longer than he had hoped to join the Mets after signing with the team in late March due to a recurrence of his back woes.

But once he got to Queens on Friday, Martinez didn’t waste any time in making an impact on a lineup that needs it.

He singled in his first at-bat and then smoked an RBI double in the sixth, both to the opposite field, in the Mets’ 4-2 loss to the Cardinals at Citi Field.

J.D. Martinez rips an RBI double during the sixth inning of the Mets’ 4-2 loss to the Cardinals. Robert Sabo for NY Post

But Martinez whiffed to lead off the bottom of the ninth.

The 36-year-old made his debut with the Mets after missing nearly the first month of the season, coming off just three minor league rehab games.

“I just tried to go up and be competitive,’’ Martinez said. “That was my whole thing today: put the ball forward. I did it twice. … To me, I was just getting my bearings and getting into a routine again.”

“He’s the same hitter we’ve seen over the years,’’ Carlos Mendoza said following the game.

The delayed start to Martinez’s season came after he watched from Port St. Lucie as the Mets got off to an 0-5 start, when he had one thought as he tried to get back to the majors after signing with the team in late March: “Hurry up.”

That helped result in a recurrence of the lower-back tightness Martinez has dealt with since 2019, but he’s confident the cortisone shot he received will take care of the issue, since he got one last year with the Dodgers and the injury didn’t return the rest of the season.

J.D. Martinez was in the Mets’ lineup for the first time Friday. Robert Sabo for the NY Post

It has been a longer wait than anticipated for Martinez, who has remained one of the top hitters in the game when he’s healthy.

Now, he adds a right-handed bat that Mendoza put fifth in the order, right behind Pete Alonso.

“It feels good writing the lineup and putting his name in,’’ Mendoza said of Martinez. “But I don’t think it’s fair to put that pressure on him and say, ‘OK, we’ve got J.D. now.’ He makes our lineup a lot deeper, but we have a lot of good hitters here.”

J.D. Martinez played just three minor league rehab games before joining the Mets. Robert Sabo for the NY Post

Mendoza added he will be “mindful” about giving Martinez time off, but doesn’t have any rules about resting the slugger, who missed nearly three weeks with the back injury last year, as well as another injured list stint in August due to a groin injury.

Some members of the rest of the lineup aren’t performing up to their usual standards and the Mets are hopeful Martinez makes everyone better.

“There are good hitters in this lineup,’’ Martinez said. “They struggled early and got things going later. These are all really good players: [Francisco] Lindor is not gonna hit what he’s hitting [now]; [Brandon] Nimmo isn’t gonna hit what he’s hitting. It’s the law of averages.”

Martinez played just three minor league rehab games after returning from his back injury and said he wants to get his timing back while in the majors as opposed to spending more time getting ready at Triple-A Syracuse.

“My body feels good,’’ Martinez said of why he believed he’s prepared to contribute in the majors. “There’s nothing like facing big-league pitching. I’ll try to grind through here and help as much as I can.”

His new teammates are looking forward to it — including the ones that have had to face him in the past.

Luis Severino has seen firsthand how dangerous Martinez can be. Martinez is 10-for-22 with a pair of doubles, a homer and an OPS of 1.160 versus the right-hander, numbers Severino is well aware of.

“As a pitcher, I have my sequences, and I know he’s one of the smartest guys at the plate,’’ Severino said. “He watches a lot of video and he’s got a great approach. I can get to two strikes against him, but after that, it’s hard. We’ve battled.”

And he believes Martinez will be the same in Queens.

“His presence changes a whole lineup,’’ Severino said. “He’ll protect Pete and give him better pitches to hit. It’s gonna be fun.”