Most of the crowd of 10,244 was on its feet at Madison Square Garden, the Kentucky fans at full throat after Keldon Johnson hit a halfcourt shot to force overtime.

Seton Hall coach Kevin Willard looked as if he had seen a ghost, furious with himself for guarding the inbounds man. His players were stunned, seeing a hard-fought victory seemingly taken from them.

Well, all but one of the Pirates — and he helped them shake off the shock of that Johnson shot and rally in overtime for an 84-83 upset victory over the No. 9 Wildcats.

Myles Powell was admittedly in shock, too — “damn,” was his initial reaction, he said — but he couldn’t let his teammates see that. The junior star gathered the Pirates in the huddle, making sure he had everyone’s attention. Forget the shot, he told them. Stay together, he roared.

“I learned so much from [last year’s] seniors, keeping my composure,” Powell said. “I knew it would trickle down to the young guys.”

“He’s the leader of the team, that’s what he does,” sophomore Myles Cale said. “All of us had the shocked face. He told us to shake it off.”

The Pirates started the extra session as if it were a new game. They scored on their first four possessions, and they picked themselves off the mat again after Kentucky scored six straight points to take a two-point lead in the final minute. But with a chance to pull the upset, Seton Hall found the open man and prevailed on Cale’s 3-pointer with 9.5 seconds left to topple Kentucky (7-2).

When Johnson’s 3-point attempt at the overtime buzzer was partially blocked by Quincy McKnight, it set off an on-court celebration reminiscent of the one following the Pirates’ Big East Tournament title three years ago. Willard had a look of disbelief, so impressed by his young team’s resiliency in picking up the program’s first victory over a top-10 non-conference foe since knocking off No. 6 Ohio State in 1992. In the locker room, the Pirates (6-3) doused one another with water.

“These kids left it all out there,” Willard said.

“You fight to win a game, and Seton Hall, they fought to win this game,” Kentucky coach John Calipari said. “They fought and when I felt, ‘OK, we got them,’ they didn’t think that. They just kept fighting.”

Cale was at the top of the list of Seton Hall heroes. The sophomore was 3-for-17 from the field and 2-for-9 from beyond the arc at the time of the last possession. But the only shot that mattered was his last one. Not all the open looks or layups that failed to drop. He pump-faked Kentucky forward PJ Washington, stepped to the side, and sank the game-winner, by far the biggest shot of his career.

“No second thoughts. It was going up,” Cale said, when asked about his confidence taking the shot. “I’m supposed to shoot that.”

Finishing with 17 points, Cale was one of many key contributors. Freshmen Jared Rhoden and Anthony Nelson played big minutes out of necessity, McKnight produced 15 points, five assists and four steals, and Syracuse transfer Taurean Thompson posted 13 points, six rebounds and the game-winning assist in by far his best performance as a Pirate.

“When you have a freshman and a sophomore trying to battle those guys, it showed me a lot,” Willard said.

Cale’s shot capped a deliriously entertaining contest, one that started like a rock fight, but will be remembered as a classic. Powell shot the Pirates back into it, scoring 25 of his 28 points after halftime, 11 in the final 3:05. It looked as if had won it with 1.1 seconds left, after drilling a step-back, double-clutch 3-pointer from the left corner.

Willard usually doesn’t guard the inbounds man, but he never has had someone’s the size of 7-foot-1 big man Romaro Gill, either. So he put Gill on the ball. It backfired, as Johnson hit the heart-stopping shot after an additional 0.4 seconds were added to the clock.

“It was stupidity,” Willard said.

All the momentum was on Kentucky’s side. Seton Hall big men Mike Nzei and Sandro Mamukelashvili had fouled out. It was setting up to be a heartbreaker when Johnson hit another crushing shot, a 3-pointer with 43.9 seconds remaining, and Cale missed on the other end.

But after Ashton Hagans split a pair of free throws with 24.9 seconds left, the ball found Cale in the corner. Seconds later, the Pirates had their biggest non-conference victory in more than two decades, a win that could propel this suddenly surging team.

“Everybody’s confidence,” Powell said, “is going through the roof right now.”