After losing once in two years under Jones, England have lost six of their nine matches this year to slip to fourth in the world rankings.

But World Cup winner Eales says England will be contenders come Japan 2019.

"I would never underestimate his ability to turn things around, very, very quickly," Eales said.

"He's been around for a long time, and knows how to re-invent himself and tweak things within a team," he told BBC Radio 5 live.

The downturn in England's form in 2018 has raised questions over Jones' ability to maintain his famed intensity, but Eales feels the former Japan boss has the experience and awareness to take stock.

"He demands very high standards, so I can imagine the intensity of that environment will be difficult to maintain over a long, sustainable period of time," he said.

"But there is no question England will improve. Anyone who takes England lightly is a fool. They have a lot of talent in the team, and a bright guy in charge."

John Eales is one of just 20 players to have won the Rugby World Cup twice

Eales captained Australia in the early days of Jones' tenure as Wallabies boss, with the lock forward retiring after clinching the Bledisloe Cup in 2001.

He is now a board director of Rugby Australia and was inducted into the World Rugby Hall of Fame in 2007 after winning 86 Australia caps and captaining his side to World Cup glory in 1999.

"Eddie was my coach in my last four Tests," Eales said.

"I got to experience Eddie as a coach and there is no doubt he is intense, but he has a wonderful knowledge of the game and has a wonderful ability to impart that knowledge on to his players.

"I have the highest regard for Eddie as a coach."

'Inspirational' Ireland will push All Blacks

With New Zealand's dominance of the global game continuing apace, Eales says it is up to other nations to bridge the gap between them and the All Blacks.

New Zealand have won the past two World Cups, and have held the Bledisloe Cup since 2002.

"It's incumbent on other nations to bridge that gap, because it's not the first time in history New Zealand have been dominant," he said.

"You can't bring them down, you have to work out how you can get up to their level, and some countries are doing that."

Eales feels Ireland and England will both test the All Blacks when Steve Hansen's side tour Europe in November.

"Ireland's results have been outstanding, inspirational in many respects," Eales added.

"Those games are no certainties to go the All Blacks' way. The styles of Ireland and England will be contrasting to what New Zealand are facing in the southern hemisphere at the moment."