Western Bulldogs forward Cody Weightman has been subbed out of the semi-final with Brisbane with a head knock.

Weightman was replaced by Jason Johannisen at the break. Weightman had managed to kick a goal in the first half and will be a massive blow.

He is coming off the back of a four goal performance last week against the Bombers.

The Bulldogs haven't yet said if it was a concussion or not. If it is a concussion and the Bulldogs advance to the preliminary final Weightman would be unavailable under the AFL's 12-day concussion protocol.

The incident came when Weightman run into Marcus Adams who was standing his ground.

Meanwhile for the Lions, Jarrod Berry will also miss the rest of the game with a head knock.

The Lions already used their sub when Jackson Payne suffered a cut to the head but the Lions have confirmed that he didn't suffer a concussion.