GWS star midfielder Stephen Coniglio has hobbled off the MCG after landing awkwardly during a contest in the first quarter of his side's clash with Richmond.
Coniglio needed assistance from the trainers to get off the ground and was unable to put any weight on his left leg.
He came into the game with heavy knee strapping and started in the forward line, prompting SEN footy expert Kane Cornes to question his fitness prior to the game.
While assessing the incident, former Brownlow medallist Adam Cooney said "it was a clear buckle of the knee".
Coniglio will take no further part in the game.
Watch the incident in the player below: