Socceroos coach Graham Arnold and captain Mark Milligan have landed in France to give support to the Matildas' World Cup campaign.

Describing themselves as part of Australia's football family, Arnold predicted they will defeat Brazil tomorrow night.

"I was there with them yesterday at training. If I had a training session like that two days before a game, with the energy that those girls had, I'd be delighted," he said.

"The Matildas and the Socceroos, we are linked as one. They're an inspiration to Australia. It's great that Mark Milligan, the captain of his Socceroos, and his kids are coming over.

"It'd be interesting to know how many other nations' captains are here with their families to support the women's teams.

"But that's what we are ... we're a football family."

Arnold's support hasn't translated into an endorsement of the players' push for pay equality across the tournaments.

Professional Footballers Australia (PFA) and the Matildas launched a campaign to petition FIFA for improved prize money on the eve of the tournament.

FIFA will pay competing federations just 7.5 per cent of what male teams received last year at the 2018 men's event.

Football Federation Australia (FFA) hasn't lent the campaign support - and neither did Arnold when asked in Montpellier.

"It's something for the organisation and obviously the PFA," he said. "Equal rights is there.

"They work extremely hard. The women's game has come a hell of a long way in the last couple of years. You look around the world at how professional the women's game has become.

"In Australia it's no different. In Australia they're doing a great job. The game is going gangbusters at the moment.

"Those things are not for me to decide and if I say something, people will disagree. It's for the right people to make those right decisions."

The overall pay packet for the 2018 men's World Cup was US$400 million ($A575 million), whereas there's just US$32 million ($A46 million) on offer in France.

The FFA walked away with US$8 million ($A11.5 million) from their participation in Russia, which ended in the group stage.

Even if the Matildas were to win in France, FFA would pocket just US$4 million.

A deal cut between PFA and FFA sees players get 30 per cent of prize money. Individual Socceroos thus earned US$104,000 ($A150,000) for their work in 2018.

Matildas would pocket US$19,000 ($A27,000) if they leave France in the quarter finals, and less if they don't match their last-out performance.

The monstrous gulf in pay is being challenged by PFA on legal grounds, as discriminatory practice.