Even as Virginia Tech held the upper hand through the first 20 minutes, there was a lurking sense of inevitability about Thursday night’s ACC Tournament quarterfinal against 16th-ranked Florida State.

The Seminoles are the biggest and deepest team in the conference, as well as one of its most athletic. And although the Hokies play great together, they are the smallest and thinnest team in the conference.

At one point or another, big and deep was going to overcome small and shallow.

It came at the midpoint of the second half in the form of an 18-1 Florida State run, and the Seminoles managed to keep hard-charging Virginia Tech at arm’s length for a 74-68 win at Barclays Center.

That was the moment when the Seminoles’ 11-man rotation started washing over Tech, whose band of seven was playing its second game in as many days.

“That’s our thing — this team has a great depth, and that’s exactly what we do. We wear teams down,” said Jonathan Isaac, who had 11 points and 12 rebounds, including five of FSU’s 18 offensive boards. “So we already know what’s going to happen. When we start off slow, we’re in the locker room saying we’re going to wear them down, because that’s what we do.”

The second-seeded Seminoles (25-7) will make their fourth appearance in the ACC semifinals — and first since they won the 2012 championship — Friday night against No. 22 Notre Dame.

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Dwayne Bacon added 17 points and Terance Mann had 11 points and nine rebounds, including six on the offensive glass for FSU.

Zach LeDay had 22 points and Seth Allen added 17 for Virginia Tech (22-10), which is a virtual lock to return to the NCAA Tournament for the first time since 2007.

As the Seminoles kept using offensive rebounds to score 10 second-chance points in the second half, it clearly affected the Hokies.

“Offensive rebounds, it affects every team,’’ Isaac said. “When that other team gets offensive rebounds and puts it back, you kind of feel helpless.”