GREENSBORO, N.C. -- Maryland had the energy, and the Terrapins had Dez Wells.
It was the right combination to knock off second-ranked Duke on Friday night.
Wells scored 30 points while the Blue Devils suffered through a miserable shooting performance from the perimeter, allowing the Terrapins to pull off an 83-74 stunner in the Atlantic Coast Conference tournament quarterfinals at the Greensboro Coliseum.
"I'm trying to be an energy guy for this team," Wells said. "I just wanted to get my guys energized."
Duke had no match for that, something coach Mike Krzyzewski noticed right away.
"We didn't play like it was one-and-done tonight," Krzyzewski said. "They did, and they won. They were the hungry team. I didn't think we were hungry. (Maryland is) trying to survive, and they played like that. They were superb."
Maryland (22-11) will play in Saturday afternoon's second semifinal against the winner of Friday's Florida State-North Carolina game.
Seventh-seeded Maryland, which probably has to win the ACC tournament to land a spot in the NCAA Tournament, never trailed against Duke (27-5).
The Terrapins were strong from the get-go.
"Watching them play, I think they fully expected to win this game," Maryland coach Mark Turgeon said of his players.
Wells, who's in his first season with the team after transferring from Xavier, was the aggressor early on and again down the stretch.
"First, I had to figure out how to coach Dez," Turgeon said. "We knew Dez was a big-time player. Tonight was a big-time performance for him."
Wells, a sophomore guard, scored 21 points Thursday in a victory against Wake Forest. He picked up where he left off the next night.
"He has elevated himself to a really high level, and you can bring everyone with you," Krzyzewski said of Wells.
Four other Maryland players -- Nick Faust, Alex Len, Jake Layman and Seth Allen -- scored 10 points each.
Mason Plumlee scored 19 points to pace Duke, which shot 4-for-25 on 3-point attempts. Rasheed Sulaimon added 16, and Seth Curry had 15.
Duke's quest to land a No. 1 regional seed for the NCAA Tournament could be damaged even though it won five of its last six regular-season games after losing Feb. 16 at Maryland. Four of those victories were by double-digit margins, and the other came against ACC regular-season champion Miami.
"I don't see any positive right now," Curry said. "We wanted to come into this tournament and play well. We took a step back. ... We need to be sharper. We need to play a lot harder from the start."
Maryland scored five of the first seven points in the second half to lead 39-28. A four-point play by Curry ignited an 8-2 run, causing Maryland to call timeout.
Duke was within 45-44 on Ryan Kelly's three-point play before the Terrapins took off again, cranking their lead to 65-52 with less than six minutes to play.
"They seemed to always have an answer," Plumlee said. "That's what prevented us from getting back."
The Blue Devils were within 67-60 with four minutes to play. Wells scored Maryland's next four points.
Duke fell to 17-1 all-time against the tournament's No. 7 seed.
Turgeon, who pointed out that the second victory of the season against Duke is bound to be good for his relationship with his fan base, said he thinks the Terrapins pounced on opportunities in the opening minutes.
"They missed some shots for us," Turgeon said. "I think our press kind of confused them early. ... I think pressing early kind of got us going. We got confident."
Maryland held a 12-point lead before settling for a 34-26 halftime advantage. The lead was built mostly on the strength of six 3-point connections.
"I sensed it right away," Krzyzewski said. "You do this long enough, you know this just isn't right."
Maryland bolted to a 12-2 edge, and that set the tone for the opening half. The Terrapins drained four 3-point shots in slightly more than 10 minutes, giving them a 22-14 lead.
At that point, Wells had 14 points, matching Duke's team total. Sulaimon came off the bench to score 10 of his team's first 14 points.
Duke made only one of 10 attempts from 3-point range in the first half, a startling development for a team that entered the game with an ACC-leading 41.6 percent shooting clip on 3-pointers.
NOTES: The teams split regular-season games, with Duke winning 84-64 on Jan. 24 at home before losing 83-81 on Feb. 23 at Maryland. ... Duke was the No. 2 seed in the tournament for the third year in a row. ... Duke's most recent game in the Greensboro Coliseum was its stunning loss to Lehigh in its NCAA Tournament opener last March. ... The Blue Devils entered the tournament having won 11 consecutive ACC quarterfinal games when receiving a first-round bye. ... Maryland's defense ranked first in the ACC in field-goal percentage defense, holding opponents to 37.9 percent shooting from the field in the regular season. ... Duke's Ryan Kelly, who returned for the final three games of the regular season after sitting out with a foot injury, didn't play in either regular-season game against Maryland this season. This was Duke's first loss in 19 games with Kelly in the lineup. He scored eight points Friday.