The final score of one of the most anticipated college basketball games of the season quickly turned into an afterthought on Wednesday night when the star Duke freshman Zion Williamson left the game with a bizarre injury within a minute of the opening tip-off.

Williamson, who is widely expected to be the top pick in the N.B.A. draft later this year, appeared to twist his left foot as his sneaker fell apart — with the sole literally breaking off at the seam — while he made a move near the free-throw line. Falling backward, Williamson reached for his right knee after falling to the court.

He walked off the court and briefly tried a new pair of sneakers on the bench, but then left the court for the locker room and did not return. After the final whistle, Duke announced that Williamson had sustained a sprained knee.

“We’re very concerned about Zion,” Coach Mike Krzyzewski said. “It’s a mild knee sprain. We will know about length of time tomorrow. It’s stable.”