Sources told ESPN that Sproles suffered the setback at Wednesday's practice and is now expected to miss the NFC East clash.
The three-time Pro Bowl selection hasn't played since the Eagles' Week 1 win against the Atlanta Falcons. He had five carries for 10 yards and four catches for 22 yards in that season-opening clash. Sproles practiced for the first time on Wednesday since missing the rest of the Eagles' games.
Sproles initially went down with the injury during a Week 2 practice session.
Eagles coach Doug Pederson called Sproles "day-to-day" and a "little bit limited" when he met with reporters on Wednesday. He also said the Eagles have a plan in place for a punt returner if Sproles were to miss the game.
The Eagles waived fellow return man DaAndre Carter on Tuesday and signed defensive tackle T.Y. McGill in a corresponding transaction. Carter, 25, had 103 yards on 10 punt returns this season. He also piled up 204 yards on 10 kick returns.
Sproles, 35, plans to retire at the end of the 2018 season.
The Eagles host the Cowboys at 8:20 p.m. on Sunday at Lincoln Financial Field in Philadelphia.