Game 4 was canceled.
From the Official Site
COLUMBUS, Ohio - Heavy rains throughout the morning and tornado warnings in the early afternoon, plus the threat of additional heavy rain, has forced the cancellation of the game Sunday between Ohio State and Illinois at Bill Davis Stadium. The game will not be made up.
Illinois won the first game of the series, 9-4, and Ohio State came back to win games two and three by scores of 9-2 and 14-8, respectively.