The FCS All-American is hoping to avoid surgery on a torn posterior cruciate ligament which coach Andy Talley said Tuesday will sideline Robertson indefinitely.
The 2014 FCS Player of the Year injured his knee on a carry in the fourth quarter of Villanova's 28-21 win over Delaware on Saturday.
His backup, redshirt freshman Zach Bednarczyk, came off the bench to rally Villanova to the come-from-behind victory, throwing for a touchdown and running for the game-winner over the final 6:18.
Bednarczyk, who completed 4 of 6 passes for 57 yards and flashed his mobility in the brief appearance, will start Thursday night when the fifth-ranked Wildcats (2-1) host Penn (0-1).
"He has the same stuff that John has," Talley said. "He can throw, he can run. He's as fast as John is, he's a really good runner. What he doesn't have is a total grasp of the offense for the last four years. John was a master of our offense."
Robertson has accounted for 10,933 total yards (7,290 passing, 3,643 rushing) and 113 total touchdowns (65 passing, 48 rushing) in his standout career. This season, he has completed 43 of 74 attempts for 522 yards, three touchdowns and one interception, and carried the ball 50 times for 138 yards and three scores.
Robertson has faced other injuries in the last year. He played some of his junior season with a fracture in his non-throwing hand and later missed Villanova's loss to Sam Houston State in the FCS playoff quarterfinals with a concussion.