Tim Cahill is privately plotting to play on for years in a welcome development that could have the Socceroos superstar appearing at a fourth World Cup.

Most assumed Brazil 2014 was Cahill's World Cup swan song.

But in a revelation that will hearten Australian football fans, the country's all-time leading goal-scorer says retirement is not in sight and he feels like he could play until he is 40.

Cahill revealed he turned down the chance to return to the English Premier League after this year's World Cup, preferring to remain with the New York Red Bulls in the MLS because he believes playing in America helps prolong his international career.

"Listen, I was 35 this month and my weight hasn't changed, my fat hasn't changed in 18 years," Cahill said ahead of next month's Asian Cup in Australia.

He put his career longevity down to desire and playing for the right reasons.

"I've gone to the MLS because that allows me to play internationally.

"The next decision that I make will still allow me to play internationally.

"But I average 30 or 40 games every season since I was 17 years old and nothing's changed.

"So I'd like to say that the next contract I sign will be two to three years minimum - with a vision."

Cahill is already in elite company alongside Dutch superstars Robin van Persie and Arjen Robben, German great Miroslav Klose and American Clint Dempsey as the only players to score at the 2006, 2010 and 2014 World Cups.

Helping Australia qualify for - and then competing at - the 2018 World Cup in Russia would be an epic accomplishment and vault arguably Australia's greatest player into a group of legends including Pele and Maradona to have featured at the global showpiece on four occasions.

Only German Lothar Matthaus and Mexican Antonio Carbajal have played at five World Cups.

"The future's bright," Cahill said.

"I've got another year left on my New York Red Bulls contract. The main feeling for me is every time I'm at a club, I like to be there for a long time.

"To be totally honest, I could have gone back to the Premier League on loan after the World Cup and I decided to stay with Red Bulls for the remainder of the season and still (have) options to go back to the Premier League if it's the right one for me - and then deciding what's best for international football afterwards as well.

"So when you put everything into one, the decision I make will be a methodical one, like I've always made it.

"It will take a month or so but, when it does, I think people will be quietly impressed with what I'm trying to do."

More immediately, Cahill said he was feeling refreshed and looking forward to entering camp with the Socceroos in Melbourne on Sunday ahead of their Asian Cup opener against Kuwait on January 9.

"Physically, I feel great. Mentally, I'm always switched on," he said.

"It seems like the calendar's worked well coming into this competition.

"I'm ready to go."

AAP