Otto Porter Jr. carried the Hoyas again.
Porter scored all but one of his 22 points after halftime and drove for the game-winning basket with eight seconds left in the second overtime, as No. 7 Georgetown pulled out a miraculous 79-78 road victory over Connecticut.
Georgetown blew a 12-point lead in the final four-plus minutes of regulation when Omar Calhoun made a game-tying 3-pointer with 2.2 seconds on the clock.
The Hoyas then found themselves down by seven in the last two minutes of the second OT before a pair of 3-pointers and Porter's driving bucket past three defenders gave them a 79-78 lead with eight ticks left.
Huskies guard Ryan Boatright, who missed a buzzer-beater at the end of the first extra session, was forced into the corner and came up empty on a desperation try as time expired.
"That was a hell of a basketball game right there," Georgetown head coach John Thompson III said. "We had our chances to end it. We didn't. Then we could have cashed it in. We fought and fought and fought."
The thrilling win marked the 10th straight for Georgetown (22-4, 12-3 Big East), which stayed atop the Big East standings with another tough road win after ending Syracuse's lengthy home winning streak last Saturday.
DeAndre Daniels paced the Huskies with 25 points and 10 rebounds in a matchup that had a tournament feel.
UConn (19-8, 9-6), which is banned from postseason play, lost for the first time in six games this season at Gampel Pavilion, though it appeared ready for a signature win after scoring six straight points in the second OT.
Porter, fresh off netting 33 of Georgetown's 57 points against the Orange, pulled the Hoyas within 78-74 with a triple, and D'Vauntes Smith-Rivera hit another from long range inside one minute to play.
After Shabazz Napier was forced into a turnover along the baseline, Porter attacked the rim and got his layup to fall. Boatright dribbled most of the remaining clock away and was surrounded by defenders as his attempt hit off the backboard, then the rim to end the dramatic affair.
"It actually felt good coming off my hands, but it fell short," Boatright said.
The first half was the polar opposite of dramatic.
Porter only attempted one field goal and missed, while Napier, UConn's leading scorer, was held without a point. Napier ended his drought with a driving layup on the first possession of the second half.
The bucket gave the Huskies a 24-19 lead, but the aggressive guard rolled his right ankle on the play and left to have it evaluated.
With Napier on the bench, Georgetown took advantage with a 22-6 flurry. Porter got going with seven points during the stretch, and Smith-Rivera drained a 3-pointer for a 41-30 lead with just over 13 minutes remaining in regulation.
Napier re-entered a little later, but the Huskies didn't make their push until there were just over four minutes to play. Two Daniels free throws finished a 9-0 run that got UConn within 60-57, but Smith-Rivera stole a lazy pass by Napier near midcourt and went in for a layup for a five-point lead.
The comeback appeared to come undone when Boatright missed the front end of a 1-and-1 with 51.6 seconds showing. Instead of fouling, UConn played defense and caught a break when Nate Lubick was called for a moving screen.
A Calhoun putback cut the deficit to three, before Georgetown's Markel Starks had a chance to ice it at the free throw line with 10 seconds to go. But Starks, too, was short on his lone attempt, and UConn rushed the ball up the court to Calhoun, whose triple from the left wing went through for a 62-62 game with 2.2 seconds left.
After a Georgetown timeout, UConn's Niels Giffey stole the inbounds pass at the arc, but his clean look came up well short as the buzzer sounded.
It was 69-69 inside the final minute of the first overtime, and Georgetown retained possession after Napier missed a tough fadeaway. With time winding down, Daniels got a piece of Porter's turnaround from the left block, and Boatright's running leaner at the buzzer was off the mark.
"The first half was not good basketball for both sides, offensively, but I think we gave everybody in the building a great game in the second half and those two overtimes," Connecticut head coach Kevin Ollie said.
Georgetown is riding its longest win streak against conference opponents since winning 10 in a row during the 2006-07 season ... UConn entered the contest with a 5-0 record at Gampel Pavilion ... Napier finished with 16 points on 6- of-16 shooting ... Starks checked in with 19 points ... The Hoyas shot 58.3 percent from the field after halftime. They shot 28.6 percent in the first half.