Despite what coach Mike Krzyzewski termed "a really good workout" by the freshman on Thursday, Williamson missed his fifth full game as he continues to recover from a sprained right knee, which he suffered Feb. 20 in the opening minute of Duke's loss to the Tar Heels.
Krzyzewski had suggested all week it was unlikely Williamson would see the court, despite his returning to practice this week and showing real progress. Krzyzewski, however, said Friday that he would "be surprised if [Williamson] doesn't play in the ACC tournament."
Duke (26-4, 14-3 ACC) is 3-2 in the nearly five full games without Williamson, who is averaging 21.6 points and 8.8 rebounds as he's made himself a candidate to be national player of the year and the No. 1 overall NBA draft pick.
Williamson suffered the knee injury when his sneaker split during Duke's first matchup against the Tar Heels last month. The injury happened on the Blue Devils' first possession of the game, and UNC went on to an easy win.
Duke dropped a game at Virginia Tech the following week and squeaked by last-place Wake Forest by just a point on Tuesday without Williamson in the lineup.
Krzyzewski noted that Williamson's injury, which followed a shoulder injury to Tre Jones and an illness from Cam Reddish earlier this year, means Duke will have played just nine of 18 ACC games with its full lineup of starters.
Krzyzewski said he's not concerned about how recent struggles without Williamson might affect NCAA tournament seeding.
"Playing with not a full deck has been very difficult," Krzyzewski said. "But I'm not going out politicking."
UNC coach Roy Williams on Thursday said the Tar Heels (25-5, 15-2) were preparing as if Williamson would play, but "why worry about that part of it?"
The Associated Press contributed to this report.