Virginia Tech guard Seth Allen made a driving shot in the lane with three seconds left in double overtime to give the Hokies a 80-78 upset victory over No. 12 Virginia in an Atlantic Coast Conference game on Sunday night in Blacksburg, Va.

Virginia's London Perrantes shot a 3-pointer from just past midcourt as time expired, but the attempt banged off the backboard.

"We were fighting all night," Allen said. "Winning this game is big, really big, because it shows what we're capable of doing because Virginia is a tough team."

The second overtime was a microcosm of the game with two ties and six lead changes.

Justin Robinson's two free throws with 37 seconds left gave Virginia Tech (17-7, 6-6 ACC) a 78-76 lead.

After Virginia coach Tony Bennett used his final timeout, Cavaliers guard Devon Hall made a layup with 17 seconds remaining to tie the game.

Allen, who led the Hokies with 20 points, then made his winning shot after a two-step jump stop, making two defenders fall back giving him an open look.

"I'm thankful the coaches trust me with the ball in my hands in that situation," Allen said. "I was fatigued in the first overtime, but I was able to get back in it in the end."

Virginia has won nine of its past 11 meetings with Virginia Tech, which also upset the Cavaliers last year in Blacksburg.

Perrantes led the Cavaliers (18-6, 8-4) with 22 points. Kyle Guy added 12 points, Marial Shayok had 11 and Hall 10.

Virginia Tech's Justin Bibbs had 16 points -- all after halftime. Zach LeDay added 11 points and six rebounds, and Khadim Sy scored 10 points.

"The only reason why we won was because of their resiliency," Virginia Tech coach Buzz Williams said of his players. "To come back from 14 points at halftime against a team that plays as slow as Virginia is amazing.

"Because of the character or the grit of our guys, we were able to win. Virginia is not a team that beats itself; you have to beat them."

Bennett said one reason why Virginia failed to hold on to a 14-point halftime lead was because of a 14-of-24 performance at the free-throw line.

Freshman Ty Jerome missed the front end of a one-and-one situation with nine seconds left in regulation, and Virginia Tech's Ty Outlaw got a tip-in on the other end with one second left to force overtime at 63-63.

Virginia made 5 of 8 free-throw attempts in the overtimes. The only time in those periods that consecutive free throws were made was when Perrantes sank two with 2:15 left in the second overtime.

"We missed too many free throws and we did not take advantage of the chances we had," Bennett said. "It was one of those wild games. A lot of the guys were drained, and you can see that. We had chances to ice it at the free-throw line, but we didn't do that."

Virginia scored 13 unanswered points in the last 4:37 of the first half, building a 37-23 lead at halftime.

The Hokies led 2-0 with 19:16 left in the first half, and they didn't take the lead again until Ahmed Hill made a layup with 3:50 remaining in regulation to put them ahead 58-57.

After Allen missed a 3-pointer for the Hokies, Perrantes drove the ball to hoop for a layup to give the Cavaliers a 63-61 lead with 26.3 seconds remaining.

Following another missed layup by Allen, the Hokies had to foul three times to get Virginia into the bonus. That was when Jerome missed the free throw setting up Outlaw's tip-in.

In the first overtime, after Perrantes made a layup with 1:03 left to put the Cavaliers ahead 68-65, Bibbs made a 3-pointer to tie the game with 51 seconds left.

Perrantes missed a layup and Allen missed a 3-pointer at the buzzer, forcing the second overtime.

NOTES: Virginia ranked first nationally in scoring defense (54 points per game) and second in turnovers per game (9.9) entering the game. The Hokies gave the ball away 17 times. ... The Cavaliers are 5-2 in their past seven games against Virginia Tech at Cassell Coliseum. ... The Cavaliers defeated the Hokies 71-48 in Charlottesville on Feb. 1. This is the shortest time between games since the Hokies joined the ACC in the 2004-05 season. ... Virginia Tech's Justin Bibbs is 46 points shy of 1,000 for his career, and Zach LeDay is 87 points off the same mark.