Geelong captain Joel Selwood has suffered a concussion in the opening minute of the Cats' clash with Fremantle this afternoon.

Selwood was knocked out due to a clash of heads as he attempted to tackle Docker Hayden Ballentyne and he lay motionless on the ground for several minutes.

Play was stopped for several minutes and the stretcher was brought out for the Cats' skipper, however, he managed to get to feet and after some assistance from trainers even managed to jog off to the interchange bench.

GEELONG, AUSTRALIA - JUNE 25: Joel Selwood of the Cats comes off the ground after he was knocked out during the round 14 AFL match between the Geelong Cats and the Fremantle Dockers at Simonds Stadium on June 25, 2017 in Geelong, Australia. (Photo by Robert Cianflone/Getty Images)

He went down to the rooms and returned shortly after with his tracksuit top on, indicating he is likely to miss the rest of the match.

Ballantyne, who received a free kick for a high tackle in the same passage of play, missed the shot on goal following the restart.