Lions QB Matthew Stafford left Sunday's 48-24 loss to the Chicago Bears with a right knee injury.
Facing a 3rd-and-6 at the Chicago six-yard line in the fourth quarter, Stafford was sacked by Adewale Ogunleye and had his leg twisted on the play.
Stafford was replaced under center by Daunte Culpepper.
Stafford went 24-for-36 with 296 yards, one touchdown and one interception for the 1-3 Lions.
It was announced after the game that he will have tests done on the knee in Detroit.