Remarkably, the Deseret News Deseret News reports that Williams escaped serious injury (Williams' ankle appeared to contort in an unnatural manner):
"A statement from the team said Williams sustained an inversion sprain, but that X-rays on the ankle — which appeared to bend quite awkwardly — were negative for any sort of bone fractures.
Inversion is the most common form of ankle sprain, occurring when the foot is turned or rolled inward."
Williams underwent an MRI which revealed no damage to the bone or tendons around the ankle. But due to the severity of the sprain, Williams will miss at least two weeks of the NBA regular season.