"We won't do this piece of work in isolation to the composition of the bench," Greenberg said. "People need to understand that composition of the bench may be made up of both interchange players and substitute players.

"That hasn't been in the game for a long time and we will do that in consultation with our medical staff and the chief medical officers of the clubs to ensure that there is that balance between the interchange and also to make sure when players are injured and can no longer participate that the clubs aren't disadvantaged." Replacements were allowed on the bench from 1970 until 1990, with the number varying between two who had played in a lower-grade game to four, who initially comprised of two fresh players and two who had played at least half a game before becoming all fresh reserves.

The interchange rule was introduced in 1991 and has shifted between six and 12 interchanges, andbeing unlimited at times.

Greenberg agreed the changes could be the most significant to the game since the number of interchanges was altered from unlimited to 12 in 2001 before being capped at 10 in 2008.

"It is a big decision for the game, it will have a big impact on the game but equally I think it will have great positives for the game as long as we do the work behind the scenes," he said. "These are changes we are looking at for the future of the game."