Manager Mickey Callaway told Asdrubal Cabrera he had the day off Sunday.

The Mets manager’s pants were no doubt in flames while his nose grew exponentially when he made that statement.

“It’s never off,” Cabrera said. “In the National League, it’s never a day off. You’ve got to be ready to play the game.”

And so the veteran Cabrera stayed ready — and got really ready about the fifth inning so he’d be prepared when the call to go to work came. That call came in the seventh, when Cabrera stepped up in a tied game with one on and two out.

Diamondbacks reliever Jorge De La Rosa tried a 2-2 slider and Cabrera turned on it for his seventh homer of the season, third pinch-hit homer of his career, the biggest hit in the Mets’ 4-1 victory to complete a three-game sweep at Citi Field.

“That’s hard to do, especially when he’s expecting an off day to relax mentally and physically,” Callaway said. “To lock it in and come in and get the job done like that, he’s not a bench guy that knows he needs to stay locked in all the time.

“For him to not play and still lock it in about the fifth and go in and take some swings,” Callaway added, “and know he’s going to be available and then come out and hit a big homer shows the type player he is.”

Reliable is one word that comes to mind.

Callaway admitted the game had the feel of so many games the Mets have been playing for weeks — close games that ultimately turn into frustrating games. The feel Cabrera had was knowing the call to hit would come. So when does he prep?

“It depends on how the game is going,” said Cabrera, hitting .321 for the season. “Today I knew we might have a situation where I can come hit and I was ready — fifth inning, yeah, I started to warm up and try to be ready for that AB.”

Noah Syndergaard was the equalizer of sorts, limiting Arizona to just one run in seven innings.

“When we get pitching like that, we’ve got more shots to win,” Cabrera said.

And even more when the “big hits,” as Callaway called them, materialize after weeks of dormancy. Tomas Nido singled with two out, then Cabrera fouled off four pitches after jumping ahead 2-0. Then came the damage.

“He hung a slider in the middle. He’s a very good pitcher. I was looking for fastballs early and he threw me a few changeups,” Cabrera said. “And on that pitch, I just tried to find the gap.”

Instead he found the seats in left for a 3-1 lead.

All in an off-day’s work.