Philadelphia Eagles cornerback Ronald Darby is out for the rest of the season after tearing his ACL.
The Eagles were forced to go with backup Chandon Sullivan during Sunday's matchup against the Dallas Cowboys. Sullivan is an undrafted free agent.
Starting cornerback Jalen Mills has a foot injury and was already ruled out. Eagles nickel cornerback Sidney Jones also missed the game with a hamstring injury.
Darby's injury comes after Ezekiel Elliott and Dak Prescott left the defending Super Bowl champions wondering how their season went wrong.
Elliott had 151 yards rushing and his go-ahead 1-yard touchdown run in the fourth quarter helped the Cowboys beat the Eagles 27-20.
The Eagles fell to 4-5 with their third straight loss at home while the Cowboys improved to 4-5. Washington leads the NFC East at 6-3.