Detroit Lions safety C.J. Gardner-Johnson suffered a potentially serious non-contact knee injury during Monday morning's NFL training camp practice at Allen Park.
He could not put pressure on his right leg and was carted off the field in agony.
The Lions lured Gardner-Johnson, 25, in March with a one-year contract worth up to $8 million. He tied for the NFL lead with six interceptions in 12 games last season for the Philadelphia Eagles.
He was a fourth-round pick by the New Orleans Saints in the 2019 NFL draft out of Florida.