CLUBS have been warned not to try exploiting the AFL's new concussion substitute process.  

"It's what the club's wanted. They've been told not to exploit it and we've got to take them at their word," League chief executive Andrew Demetriou told AFL.com.au.  

"I've said before the days are gone people trying to cut corners," he said.  

"It's there for legitimate reasons."

There have been some questions raised about whether the new system, implemented just days before opening round, will beworkable.

Demetriou wants to avoid any mid-season tinkering.

"Hopefully not, I think it's a sensible compromise," he told AFL.com.au.  

"We're pleased that we're adopting a very sensible and conservative approach to the treatment of concussion.

The rule allows a substitute wearing a green vest to replace a potentially concussed player for up to 20 minutes.

If they injured player is cleared to return, the original sub returns to the bench, and can put the green vest back on.

But a healthy player, already subbed off and wearing the red vest, is not able to return to replace a concussed player.

Matt Thompson is a reporter for AFL Media. Follow him on Twitter @MattThompsonAFL