Socceroos goalkeeper Mark Schwarzer says qualifying for the World Cup must come ahead of allowing opportunities for the next generation.

Mark Schwarzer eats steak for breakfast but it's with critics of the Socceroos' ageing population that he has a serious beef.

Schwarzer will be closing in on his 42nd birthday by the time the 2014 World Cup begins in Brazil and he's regularly asked about his vintage and the importance of developing the next generation for Australia.

He is not alone as several other key Socceroos will be in their mid 30s there, if Australia reach the sport's showpiece tournament for a third straight time.

"Sometimes I have to scratch my head and I have to completely turn off," Schwarzer said ahead of Friday's (11pm AEST) World Cup qualifier against Oman in Muscat.

"We need to look to the future, it makes sense of course.

"However the problem is if you don't have your strongest team week in, week out, and in qualification, you're not going to qualify for another World Cup.

"That's going to have massive ramifications on the game itself."

The Fulham goalkeeper, who debuted for Australia nearly two decades ago, is on an "extreme" diet designed to defy the ravages of time.

He admitted his eating habits, such as eating steak in the morning, turned heads but the sacrifices were worthwhile.

"They (teammates) would probably say that I am extreme," he said.

"But I don't see it as being extreme anymore.

"I actually enjoy it.

"I see the difference in myself and my own appearance and also how I feel."

He strongly believed advances in sports science allowed players to extend their careers.

"All the indications are there," he said.

"When you look at the leagues around the world, players seem to be going longer and staying fitter, and staying at the highest level longer than ever before.

"I don't know if people register that. I don't know if people take note of it."

Australia is still waiting for the next generation of players to put pressure on the senior Socceroos.

"In our squad there are a couple of younger representatives," coach Holger Osieck said.

"Rhys (Williams), (Matthew) Spiranovic, (Robbie) Kruse, (Michael) Zullo ... but the other ones who are not in the loop right now are being monitored, but they still have a long way to go."

Schwarzer said it was up to Osieck to pension off the older players.

"The reason why most of us at the older age are still playing, is because I truly believe we're probably still the best players to play for the country," he said.

"If that was any different, the manager would definitely do something about it."