Michigan leads Purdue 31-13 early in the fourth quarter Saturday at Ross-Ade Stadium.
The Wolverines added a field goal for the only points in the quarter.
Robert Marve, who suffered a knee injury Sept. 8 at Notre Dame, entered the game at quarterback late in the third quarter.
He helped lead Purdue to a field goal early in the fourth quarter.
Purdue has had no success on third downs. Purdue was 1 for 9 in those opportunities after three quarters.
Michigan quarterback Denard Robinson has 105 passing yards and 153 rushing yards.