Mets' Brandon Nimmo lays on the ground after an injury...

Mets' Brandon Nimmo lays on the ground after an injury against the Phillies in Game 1 of a doubleheader at Citizens Bank Park on Thursday. Credit: Getty Images/Mitchell Leff

PHILADEPLHIA — When a groundout off his knuckle rolled to third, Brandon Nimmo hit the ground and stayed there, writhing in pain as he held his shaking left hand. A minute later, as he slowly stood up and made his way back to the Mets’ dugout, he had one thought: Hopefully the direct hit didn’t result in a break.

X-rays on Nimmo’s left index finger were negative. He is scheduled for an MRI on Friday.

“I saw the ball go [toward third] and I was like, ‘Ah, crud!’ ” Nimmo said. “And then I felt the pain and I was like, ‘Oh, crud, it hit my finger!’ and went to the ground.

“It definitely had a lot of pain…It looked like I bunted it down to the third baseman. I’m very fortunate that this isn’t more serious as of now.”

Jose Bautista replaced Nimmo in rightfield in the Mets’ 24-4 win against the Phillies and racked up a career-high seven RBIs, the first player in Mets history to do that in a game he didn’t start.

For Nimmo and his swollen, bruised finger, the hope is to learn from the last time this happened. When he got hit in the hand by a pitch in late June, he took a couple of days off before returning — and slumping. He was hot again recently, reaching base in 10 consecutive plate appearances before the unusual groundout.

“I guess it’s a learning experience from last time, of what I’m looking for as far as strength and feel in my hand,” Nimmo said. “We’ll try to be a little more diligent on this one about coming back the right way.”

Visiting Cabby

Three weeks after picking up 14 games in the standings, a new temporary home city and his old position, Asdrubal Cabrera is settling in nicely to life with the Phillies — and life in a playoff race.

As the Mets visit the Phillies, Cabrera is facing off against his old teammates for the first time since his July 27 trade. He is an everyday shortstop, a role he never thought he’d have again after moving off the position last summer, and has enjoyed being around a young Phillies team that has turned into a surprise contender, two games back of the Braves in the NL East at the start of play Thursday.

“When a team like this wants you on the team to try to help make the playoffs, that’s real good,” Cabrera said. “We’re in a good position right now. I hope we make it. We’re playing really good baseball right now, so keep doing what we’re doing and I hope we make it.”

Extra bases

Former Mets closer Jenrry Mejia, banned for life from baseball two and a half years ago, began a rehab assignment Thursday, per the terms of his potential reinstatement this offseason. He tossed four shutout innings for one of the Mets’ Dominican Summer League teams…Jacob Rhame joined the Mets as the 26th man for their doubleheader Thursday, the latest step in a doozy of a recent travel schedule. After the Mets’ game Sunday in Miami, Rhame was optioned to Triple-A Las Vegas and flew to Fresno, California, to join the team. He pitched a scoreless inning Tuesday before flying back across the country to join the Mets again Thursday — for a day…The Mets optioned Tim Peterson to Las Vegas to make room for Steven Matz.