Kon Knueppel scored 17 points and No. 1 Duke held off a furious second half rally by North Carolina to beat its rival for the third time this season, 74-71 on Friday night to reach the Atlantic Coast Conference Tournament championship game.

There was a development in the ACC Tournament on Thursday that could have ramifications at both ends of the bracket. Duke All-American freshman Cooper Flagg suffered a sprained ankle in the first half of the Blue Devils' win over Georgia Tech in the ACC quarterfinals.

ACC Player of the Year Cooper Flagg was ruled out for Duke's conference tournament semifinal matchup with North Carolina on Friday night in Charlotte. Flagg sprained his left ankle in the first half of Duke's quarterfinal victory over Georgia Tech on Thursday and did not return to the game.

The North Carolina Tar Heels (22-13) and the San Diego State Aztecs (21-9) will meet on Tuesday in the First Four of the NCAA Tournament.