AS THE NRL prepares to defend the validity of its salary cap, West Coast captain Darren Glass has declared the system, also used by the AFL, as necessary.

Glass said an even competition should take precedence over the extra money that would be available to players if the salary cap was removed and stood by the AFL Players Association's stance.

"The AFLPA has supported the salary cap and supports it because I think it brings equality and brings a nice even playing field to the game," Glass said on Wednesday. 

"I don't think it would be a great scenario if we ended up like the English Premier League where there are only a couple of sides competing for the title every year.

Glass plays for one of the AFL's most profitable clubs but said the rich and poor divide in the AFL only highlights the need to maintain the salary cap.