BUFFALO — Villanova could not put its finger on what was wrong and what was missing, which was a big part of the problem. The Wildcats could not even form the right question. The only thing that was clear was that Donte DiVincenzo was the answer.

The redshirt freshman guard, who was with the team that won the national title last year but not part of it, came off the bench and contributed 21 points, 13 rebounds, good defense, bundles of energy and everything else that spared Villanova an epic embarrassment. As it was, the Wildcats began their title defense with a 76-56 victory over Mount St. Mary’s on Thursday night.

This was no slam dunk, as every 1 vs. 16 seed is supposed to be. Villanova (32-3) missed its first eight shots and did not take the lead until 1:23 remained in the first half. And even the term “slam dunk” proved a bit uncomfortable because DiVincenzo missed two of those.

He did just about everything else correctly, though, in his first NCAA Tournament game. “It felt great,” he said after his first career double-double. “Throughout the year, we played in some tough environments. Even at home, we played in a crazy environment. I just focus on 94 by 50 feet.”

Those are the dimensions of every court. The basket is 10 feet high, too, as the coach in the movie “Hoosiers” pointed out to his vast underdog of a team. Mount St. Mary’s (20-16) got off to a Hoosiers-like start, sparked by 5-5 guard Junior Robinson and 6-5 forward Miles Wilson (22 points).

“They played better,” Villanova coach Jay Wright said. “We just, at the end, had more size and some more talented players that just made plays. I thought they were the better team tonight.”

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A cause for concern for the Wildcats: Wright had said almost the exact same thing after the win over Seton Hall in the Big East semifinals. If he had more time, he would organize some team-wide soul-searching. Instead, he must concentrate on getting through tomorrow’s game to reach the Sweet 16 at Madison Square Garden.

He and his players are fortunate that DiVincenzo had a coming-of-age game. It was not his highest-scoring game (he had 25 against St. John’s), but it was five more than his previous high in rebounds — including high school.

“I kind of get more enjoyment out of getting a rebound and looking up the floor and seeing one of [our] guys get a fast-break layup,” he said, adding that he improved as a rebounder by “getting beat up every day in practice last year.”

Teammate Josh Hart said, “I think he probably took a couple of mine today. He’s a freak athlete and he wants to rebound. That really sets him apart from a lot of guys.”

Believe it or not, Wright said DiVincenzo also is one of the team’s best dunkers, even though he missed twice. “The first one, I took off too far, I guess,’’ he said. “The second one, I don’t know what happened.”

No problem. “I won’t say a word about that,’’ his coach said. “I’m just so proud about how he rebounded and how he defended.”