PHILADELPHIA -- When Brandon Nimmo awoke on Tuesday morning, he felt an uncharacteristic soreness in his neck -- nothing overly serious, but notable nonetheless. He commuted to Citizens Bank Park and received some massage therapy, but otherwise he thought little of it.

Later that evening, Nimmo swung through a fastball to lead off the Mets’ 14-3 loss to the Phillies and felt his neck “lock up.” Leading off first base after drawing a walk, Nimmo struggled to hold his head up straight.

“I just felt so unnatural out there,” Nimmo said. “It just was not allowing me to do anything I wanted to.”

In the bottom of the first inning, J.T. Realmuto hit a double to left-center field that Nimmo, struggling to run and turn his head at the same time, did not come close to catching. In the Mets’ dugout, team officials noticed Nimmo grabbing his neck between pitches and decided it was time to retrieve him. As manager Mickey Callaway emerged to remove struggling starter Steven Matz from the game, trainer Brian Chicklo also jogged onto the field to fetch Nimmo.

“I wasn’t helping anybody by being out there at that point,” Nimmo said.

The Mets plan to rest Nimmo on Wednesday, and again during a team off-day Thursday, but they do not anticipate administering an MRI. Their hope is that he will be back to normal by Friday, and Nimmo has some reason to concur with that optimism. When he was 12 years old, Nimmo said, he experienced a similar issue, waking up one day unable to move his neck. He spent 24 hours in a neck brace taking muscle relaxers, and he was back to normal the following morning.

There is nothing obvious in Nimmo’s recent past to suggest a more sinister issue, save for his crash into the SunTrust Park wall after catching an Ozzie Albies fly ball Sunday in Atlanta. But Nimmo did not hit the fence particularly hard, and he did not experience any lingering discomfort at the time -- nothing until he woke up with a slight neckache Tuesday.

“I’m not really sure what happened,” he said. “I’m not sure what caused it. I’m sure we’ll try and get to the bottom of it, but nothing comes to mind right now. It was a very weird event.”

Regardless of its cause, the injury comes at an inopportune time for Nimmo, just as he was catching fire at the plate. In the eight games leading into Tuesday, Nimmo was hitting .393/.500/.821 with six extra-base hits, five walks and nine strikeouts, after producing a .077/.250/.077 slash line with no extra-base hits, five walks and 17 strikeouts in his first eight contests.

The difference was a return to his trademark plate discipline. In his first eight games, Nimmo swung at 28 percent of pitches out of the strike zone, according to Statcast data. In his next eight, he reduced his chase rate to 15 percent. Not only did that allow Nimmo to lower his strikeouts, but it also improved his quality of contact by forcing pitchers to throw him better offerings.

Now, Nimmo must find a way to maintain his gains despite a break in his routine.

“It is frustrating -- really, really frustrating,” Nimmo said. “Any time off, you start to get out of the rhythm of the game. But we’ll do our best to stay in the rhythm of it.”