PORT ST. LUCIE, Fla. — It wasn’t all that long ago that Noah Syndergaard had to keep off social media because he had been so obsessed with the idea of reaching the big leagues that he couldn’t help but check Twitter for the latest news.

Nor was it that long ago that Syndergaard spent a spring training scrimmage eating lunch in the clubhouse, earning him a swift rebuke from veterans such as David Wright.

Since then, Syndergaard has made it difficult to remember that he once was unsure of himself. And Thursday, when it was announced that he has been named the Opening Day starter, the Mets’ new ace played it cool.

He had long been the assumed choice for the assignment, and Terry Collins called it one of the easiest decisions he’s made during his seven years in the manager’s chair.

“It’s just a huge honor,” Syndergaard said. “It’s something I’ve been working for ever since I’ve been with the Mets, to be the Opening Day starter at one point. But certainly I’m thrilled that Terry instills that kind of confidence in me, so I’m just going to go out there and get the job done.”

Collins already had publicly hinted about the Opening Day start, and a few days ago he notified the 24-year-old that he would land the assignment. Nevertheless, before workouts Thursday morning, Collins summoned to his office all of the pitchers likely to make a start this season. It was there that he shared the news again.

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Collins didn’t take long to make it public. The Mets typically announce their Opening Day starter later in camp. But he saw no point in waiting to make an announcement that essentially was a given.

On April 3, against the Braves at Citi Field, Syndergaard will get the ball.

“I believe that Opening Day is something you earn from the year before, and I don’t think it should be based on what you see in spring training,” Collins said. “This guy, with what he did last year, deserved to be that guy.”

Injuries defined the 2016 season for the Mets, especially with the rotation. Matt Harvey, who started on Opening Day, had his season cut short, as did Jacob deGrom and Steven Matz. All three had surgery. Syndergaard pitched through a bone spur but emerged relatively unscathed, going 14-9 with a 2.60 ERA in 183 2⁄3 innings. For the first time, he was an All-Star.

“It’s just a great feeling, heartwarming,” Syndergaard said. “I’m excited to rise to the calling.”

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Syndergaard joins an impressive list of pitchers to receive the call. It includes Tom Seaver, Dwight Gooden, Tom Glavine and Johan Santana. More recently, the honor has gone to Harvey and an ageless Bartolo Colon, who Collins said would have been in the mix had he not signed with the Braves.

“Almost every day, I kind of take a glance back at where I was,” Syndergaard said. “It’s just an awesome feeling and it’s just only begun. I’m thrilled about where I am now but I’m never going to be satisfied.”

He again proved that, arriving in camp with 17 pounds of additional muscle, all in hopes of throwing even harder. All of it is in preparation for moments such as Opening Day.

“I can’t imagine how loud that crowd’s going to be,” he said. “Sometimes when I go out there, I try to have tunnel vision and try to tune everything out. But you can really feel the energy of the Mets faithful.”