Williams suffered the injury in a pileup under the basket late in the game against Florida State. He left the Smith Center Sunday evening with the aid of crutches.
X-rays on Monday showed a sprain, but no fracture.
Williams is averaging 9.5 points and 4.1 rebounds per game this year. He is third on the team in scoring and rebounding behind seniors Jason Capel and Kris Lang.
Ohio is 15-8 overall and 10-5 in the Mid-American Conference. The Bobcats are coming off a 71-66 win at Marshall. Tipoff is at 7:30 p.m.