The St. John’s Red Storm have touted their ability to fight through adversity.

To be at their best with their backs against the wall.

Saturday night, they showed it once again.

With their engine, Deivon Smith, mostly a second-half observer due to a right shoulder injury and the Johnnies sluggish coming out of halftime, Villanova looked like it was in control.

But St. John’s refused to disappoint the second-biggest home crowd of the Rick Pitino era. The Johnnies defended the life out of Villanova down the stretch and RJ Luis — not Eric Dixon, the nation’s leading scorer — was the best player on the floor.

Luis scored 23 of his St. John’s career-high 30 points after halftime and Kadary Richmond came alive late, as the Johnnies won for the ninth time in 10 games, knocking off red-hot Villanova 80-68 at a rocking Garden.

With the win, they improved to 5-1 in league play for the first time since the 2000-01 season, and have now beaten the Wildcats three straight times.

“It just goes to show the toughness that we have as a group,” Simeon Wilcher said.

The Johnnies (14-3, 5-1) held Dixon to 18 points on 6-of-19 shooting and hammered Villanova (11-6, 4-2) on the glass, 44-28. They also made 29-of-39 free throws, icing the game late. The Johnnies closed with a flourish, outscoring Villanova 14-3 over the final 2:05.

Luis also had 10 rebounds, becoming the first St. John’s player to produce a 30-point, 10-rebound performance since Julian Champagnie in 2022.

He took over with Smith sidelined.

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Early in the second half, Pitino pulled the standout junior very briefly. He had a message for him.

“You’re going right back in, but I want to tell you, if you don’t pick this up, we’re not winning this game,” the Hall of Fame coach recalled himself saying. “You’ve got to pick this thing up.”

Luis listened.

He scored inside and out, and went 16-for-20 at the free throw line.

At one point late in the game, he laid out like a wide receiver for a loose ball, forcing a tie-up. It was emblematic of his second half effort.

He had nine rebounds after the break, five of them offensive. Villanova didn’t have an answer for him.

“I’ve said this all along, RJ is one of the most gifted players I’ve coached,” Pitino said. “He just refused to not get rebounds with the game on the line five different times. His toughness was incredible. He got on the floor before everybody. I can’t say enough accolades for RJ tonight. Putting aside his great talent, his hustle was amazing to me.”

Richmond finished with nine points, five assists and four rebounds, Aaron Scott added 12 points and Zuby Ejiofor notched 11 points and nine rebounds.

Wooga Poplar led Villanova with 22 points.

The Red Storm did get good news on Smith, their floor general. He hurt his right shoulder with 2:02 left in the first half while going after a loose ball.

He collided with Poplar and immediately went to the locker room. He was in a sling to start the second half, but did play three minutes without taking a shot. He was clearly favoring the shoulder.

Pitino said it doesn’t look to be serious, that it popped out and back in, and Smith won’t be out long.

X-Rays were negative.

Without him, other players stepped up. Richmond was again at his best at both ends in crunch time. Wilcher had two key baskets in the final 3:30 and Luis took over in the final minutes. A key player going down wasn’t going to stop St. John’s on Saturday night.

“It just shows what type of chemistry we have. How everybody has each other’s back,” Luis said. “One [guy] goes down, the next man has to step up.”