The Carolina Panthers saw right tackle Daryl Williams carted off with an apparent knee injury on the first day of practice in full pads on Saturday.
Williams screamed in pain and clutched his right knee after being hit by defensive end Zach Moore while blocking for quarterback Cam Newton.
Teammates kneeled as trainers tended to Williams before he was carted off after five minutes.
A second-team All-Pro last season, Williams is in the final year of his contract and was in negotiations for a new deal with the Panthers.
Second-year guard Taylor Moton took Williams place on the offensive line when practice resumed.
Williams, 25, started all 16 games last season and has started 28 of 39 overall since being taken by the Panthers in the fourth round of the 2015 draft.