Clubs will be able to replace an injured or concussed player under a new medical substitute rule that has been introduced a day before the start of the season.

All clubs will name 23 players in their match-day squads instead of the regular 22, but that extra 23rd player will only be able to take the field after club doctors have assessed an injured or concussed player as 'medically unfit' to continue in the match.  

To be eligible for a medical substitution, the club doctor must decide that an injured player will be unable to play a game in the next 12 days.

Concussed players must already sit out a mandatory 12-day recovery period under new protocols introduced by the AFL for the 2021 season.

Nick Holland returns to the brown and gold

Club doctors must provide the AFL with a medical certificate on the first working day after the match as evidence the substituted player sustained the injury.

Any club found to be breaking the medical substitute rule can be sanctioned "for conduct unbecoming, or prejudicial to the interests or reputation of the AFL, or to bring the game of football into disrepute".

As a result, team selection will look a little different in 2021.

Clubs will name a 'normal' squad of 22 players and four emergencies the evening before the game, but they won't have to name the 23rd 'medical substitute' player until final teams are confirmed an hour before the first bounce. 

The new rule will only apply at AFL senior level – not in any state league or elite junior competitions.

More to come