Saturday's showdown between No. 3 North Carolina and No. 4 Duke is the headline matchup of the weekend in college basketball, but its luster is lost a bit with the expectation that Zion Williamson, Duke's star freshman, is unlikely to play.

Duke coach Mike Krzyzewski spoke with reporters on Friday in advance of the game in Chapel Hill and updated Williamson's health status. Krzyzewski wouldn't go as far as to rule Williamson out, however, his status is officially doubtful nearly 24 hours ahead of tip time.

"He had his first really good workout, but not contact. He'll have no contact today. I would say he's doubtful for tomorrow, but we'll see tomorrow," Krzyzewski said. "The way he's going, he won't be doubtful for the tournament."

Williamson was injured in the first minute of the last UNC-Duke game, on Feb. 20, when he made a move toward the basket, split his shoe and tweaked his knee. Duke, in the aftermath of testing, labeled him as day-to-day with a Grade 1 mild right knee sprain, but he's missed more than two weeks recovering and four full games not including the North Carolina game.

The recent comments do not come as a surprise. Krzyzewski indicated earlier this week, after Duke beat Wake Forest 71-70, that he did not anticipate Williamson to be ready to go for Saturday's game against North Carolina. Based on what he's observed, he expects him to be physically ready to go by the ACC Tournament.

"He's getting more confidence, and we just have to get him in shape," Krzyzewski said. "I don't think he'll be ready for Saturday. I have to be careful not to push this, but I would be surprised if he wasn't ready by the ACC tournament."

Williamson is averaging 21.6 points, 8.8 rebounds and 2.2 assists per game for the Blue Devils this season. Duke and North Carolina tip Saturday evening at 6 p.m. ET.