RUGBY league's top coaches are on a collision course with the code's administrators over the interchange rule, with plans to lower the number of allowable replacements likely to attract criticism as racist.

In an unusual alliance, referees have joined with coaches in moves to halve the number of substitutions, while club doctors have linked with administrators, who prefer the status quo.

Lowering the number of replacements from its ceiling of 12 may be seen as a strategy to reduce the influx of Polynesian players, who are perceived to have lower stamina, although some coaches say this is a myth.

Ricky Stuart, who, as a Canberra halfback midwifed changes in the game, is now seeking one himself as Kangaroos and Cronulla coach.

Stuart has been campaigning for two years to cut the number of substitutions to six, and has convinced NRL chief executive David Gallop to table it at a meeting at season's end.

Stuart and Craig Bellamy, coach of top of the table Melbourne, argue a reduction in interchange will tire players and allow the more skilful, smaller players to decide games, particularly in the closing minutes.

"We've got to get more Turvey [Steve] Mortimers in the game having a crack at the big blokes," Stuart said of the former Canterbury halfback, whose cover defence and agility exasperated the giants in the 1970s and '80s.

Stuart also says matches ending in attrition will help referees who won't be required to make as many high-speed, critical calls.

However, some leading administrators believe much of the debate is cloaked in myth, anecdote and contradiction, while maintaining the only clear evidence is medical, with doctors fearful injured players will be forced to remain on the field.

Three golden-point games in one recent round and only one blowout result last weekend are further proof games are already ending in attrition.

"It's an important debate for the game to have after the season," Gallop says.

"We need to canvass a broad range of opinions - ex-coaches, prominent footy brains, current players and coaches.

"Despite the fact there are people who would boo Santa Claus on December 25, the game is about to experience one of the most thrilling finals series ever, and changes to rules should not be implemented without careful consideration.

"The best sports in the world have a continuity about the rules, and people like to compare era with era, without feeling things are always changing.

"More fatigue may mean players are forced to play injured but, on the other hand, more attrition may lessen the brutality of the collision and less dominance by fresh forwards."

Changing the rule gained supporters two nights after the first State of Origin match last year, when halfback Brett Finch, having kicked the winning field goal for NSW, backed up for the Roosters against Parramatta, only to have prop Fuifui Moimoi come on for 10 minutes, run at him, then leave the field for 10 minutes, only to return and repeat the process.

"I'm all for lowering the number," Bellamy says. "We don't need 12. Eight would be ideal. We've got to get guys playing for longer. Call me old-fashioned, but I like to see guys battle fatigue."

He rejects the argument the move is aimed at reducing the number of Polynesian players.

"Polynesians are like white guys," he says. "Some are more aerobically fit, others are less aerobically fit. The way you train them is the important thing. [Melbourne forward] Jeff Lima [a Samoan] played for 25 minutes straight against Parramatta."

However, ARL chief executive Geoff Carr says this perception means New Zealand would probably vote against it.

"If the NRL decides to do something in a World Cup year [2008], New Zealand and Great Britain won't change the rules to suit Australia," he says.

"New Zealand have a lot of Polynesians and Maoris, and Great Britain traditionally likes big players.

"Would those countries lessen their chances to suit Australia?

"We've worked hard to unify the law book, and for the NRL to play separate rules to other nations doesn't make sense."

Carr maintains the "making it easier for the Mortimers" argument could be as mythical as the Polynesian perception.

"People say less interchange makes it easier for the little bloke, but this is anecdotal," he says.

What is certain is that NRL players have been running the player-welfare argument all year, protesting the season is too long.

Reduced interchange will result in them having more game time.

Canterbury's Willie Mason will play 70 minutes, not 60, meaning there is the possibility his coach will train him harder in the off-season in order for him to counter the little men.

NRL referees boss Robert Finch agrees reduced interchange would lessen pressure on referees but claims it is an insignificant argument to developing more skilful players.

"Collectively, I don't think the game would slow down so much that it would greatly help referees," he says, with a hint of frustration at the constant complaints against his men.

"Referees adapt to changes pretty well, and after we do something to fix things up, do we then ask what are we going to do next?"

It would seem coaches are already reducing interchange voluntarily. Titans coach John Cartwright made only eight changes against the Roosters, and Stuart admits in most games to using 10.

Strategic replacement to a coach is what wet clay is to a potter - it can take any number of shapes in the search of elusive perfection, with some works of art requiring more clay than others.