Seth Allen calmly drained two free throws with 2.8 seconds remaining to lift the Maryland Terrapins to a stunning 83-81 victory over second-ranked Duke at the Comcast Center.
Alex Len had 19 points, nine rebounds and three blocks for Maryland (18-7, 6-6 ACC), which saw Duke erase a 10-point deficit late in the second half.
Dez Wells sank a pair from the foul line to put the Terrapins up 77-67 with 3:39 to play. The Blue Devils (22-3, 9-3) closed the gap to 80-78 when Seth Curry hit back-to-back 3-pointers.
Curry, however, came off a screen and missed an elbow jumper that could have tied the game with about 30 seconds left. Mason Plumlee fouled Jake Layman, who secured the defensive rebound. After making just 1-of-2 attempts at the line, Layman fouled Rasheed Sulaimon on a 3-point try.
Sulaimon converted all three free throws, tying the game at 81-81 with 16.7 seconds left.
Allen then drew contact from Quinn Cook on a drive through the lane on the ensuing possession.
The Blue Devils had a final chance after Allen's clutch performance at the line, but their desperation runner from just past half court was off the mark.
"I am really proud of my kids," said Maryland head coach Mark Turgeon. "I worked them really hard this week and challenged them in a lot of different areas. I told them before the game you don't have to do anything extraordinary you just have to play to our level. We weren't extraordinary all the time but we played to our level, we continued to compete."
Allen finished with 16 points, while Wells posted nine points, seven rebounds and seven assists.
Curry scored a game-high 25 points for Duke, which had won six straight, beginning with an 84-64 victory over Maryland on Jan. 26. Cook contributed 18 points, Sulaimon 16 and Josh Hairston 11.
"We fought hard in the last ten minutes," Cook said. "We had a lot of players who stepped up big with all our foul trouble."
A back-and-forth opening frame ended with Maryland holding a 35-34 edge. The Terrapins grabbed their first double-digit lead at 53-43 on two Allen free throws with 14:41 remaining.
Duke had beaten 19 straight unranked opponents ... The Terrapins snapped a six-game losing streak in the series ... Maryland shot 66.7 percent (12-of-18) and made 23 free throws in the second half ... Layman, Charles Mitchell and James Padgett each had eight points for Maryland.