Australia head coach Tim Sheens says there is little to call between his team, England and New Zealand in international rugby league.
The Kangaroos are the reigning world champions, beating both nations en route to lifting the 2013 World Cup.
However, the Kiwis won the 2014 Four Nations, twice beating Australia, who only overcame England by four points.
"There's not much difference between the three nations," Sheens told BBC Radio Manchester's Rugby League Extra.
"As dominant as Australia has been, the scoreline never shows how close the games have been.
|Australia 'invincibles' show signs of waning|
|Tim Sheens had led Australia to a 17-match unbeaten run before their 30-12 defeat by New Zealand in Brisbane in last November's Four Nations competition.|
"It's coming, with the Australia side getting very much older, over the next two years England and New Zealand are going to put us under pressure and we'll have to battle."
Sheens' side, particularly the one that won the 2013 World Cup, was built on a long-standing spine that has developed and grown together in club, representative and international football.
But several members of the squad - such as playmakers Johnathan Thurston, Cameron Smith and Cooper Cronk, plus forwards Paul Gallen and Corey Parker - are all into their thirties, and Sheens believes the players bidding to replace them will take time to find the same co-ordination and combinations.
"It's about experience in Test match football," Sheens added.
"The Australia, New South Wales and Queensland sides that played against each other for the last six years are all champion players but they're all ageing at the same time.
"Australia's team that played England in the first match of the World Cup was the oldest Kangaroos side on record. There is a large part of that squad that has played State of Origin. It was a one-in-a-generation group.
"The spine of Johnathan Thurston, Billy Slater, Cameron Smith and Cooper Cronk are all 32 this year. The next World Cup in 2017 and let alone the tournament after that is going to be a big challenge.
"At the end of the day, England and New Zealand are recycling their players as well. There are champion English players like Kevin Sinfield no longer involved, it's a younger group.
"Australia are in a transition period, and that side that played in the final of the 2013 World Cup is a special group.
"But [Jarryd] Hayne's gone to America, there's a change coming and, when it changes, just where Australia are compared to England and New Zealand will be interesting."