Top-ranked Duke won’t have star freshman Cooper Flagg for Friday night’s ACC tournament semifinal against rival North Carolina, with the Blue Devils officially ruling him out about two hours before tipoff in Charlotte, North Carolina.

Flagg sprained his left ankle in the first half of Duke’s 78-70 quarterfinal win against Georgia Tech on Thursday. He hobbled off the court before heading to the locker room, then returned to the bench for the second half but didn’t play again.

It was considered a long shot that he’d face the Tar Heels, coach Jon Scheyer had said. The 6-foot-9 Flagg was already dealing with swelling after the Georgia Tech game, and Scheyer said he’d “have to be really convinced we should even consider seeing if he can go” in the semifinals Friday night. X-rays didn’t show a fracture.

Flagg, the ACC’s player and newcomer of the year, averaged 19.4 points, 7.6 rebounds and 4.2 assists during the regular season.

Duke also won’t have key reserve and defensive whiz Maliq Brown for the UNC game. Brown reinjured his dislocated left shoulder against Georgia Tech.