Former Clemson guard Brandon Thomas, who is rated as one of the top interior offensive linemen available in this year's draft, suffered a torn ACL while working out last week, a league source said.
Thomas (6-foot-3, 317 pounds) is coming off an outstanding set of practices during the Senior Bowl and was seen as a probable second- or third-round pick before suffering his injury, according to NFL personnel sources.
Thomas suffered the injury during a non-contact drill in a workout with the New Orleans Saints, a league source confirmed to ESPN.
He already had six pre-draft visits in recent weeks.
Thomas is ranked by ESPN's Scouts Inc. as the third-best guard available in May's draft.
Adam Caplan is an ESPN NFL Insider. ESPN.com Saints reporter Mike Triplett contributed to this report.