Rush is 4-0 since entering the lineup as an injury replacement for Prescott, whose initial medical prognosis called for a 4-to-6 week recovery window.
Cowboys owner Jerry Jones said Tuesday that Prescott would need to be convincing in workouts this week with his ability to "spin the football," a reference to his ability to grip the ball and throw it on target with needed velocity. Prescott was not able to fully grip the ball last week, and head coach Mike McCarthy described his practice activity on Wednesday -- four days before the primetime matchup against the host Philadelphia Eagles -- as "light throwing" on the side.