The Pelicans said Thursday that the No. 1 pick didn't travel with the team to New York, remaining in New Orleans to undergo further testing and evaluation at Ochsner Sports Medicine.
He was to have played Friday night against former Duke teammate RJ Barrett, the No. 3 pick, in a nationally televised game.
Williamson has averaged 23.3 points on 71.4% shooting in four preseason games. The Pelicans said further updates will be provided when available.