Australia's coach said his young Socceroos had the energy and verve to spring a surprise at the Asian Cup after injuries and retirements forced the defending champions into major changes.

Graham Arnold said last year's World Cup, where teenage French striker Kylian Mbappe ran riot, showed football was a "young man's game" and that he expected his players to prove it by beating Jordan in their opening game on Sunday.

"Pressure is just a word," said Arnold, who has been hit by injuries to key players Aaron Mooy, Daniel Arzani and Scottish-born Martin Boyle ahead of Australia's title defence in the United Arab Emirates.

"We have the utmost belief and confidence in what we're doing. Yes, four years ago is a long, long time. Mile Jedinak, Timmy Cahill and ex-players have retired and moved on, this is football," he said on Saturday.

"We have great depth in our squad, new players coming in, young players. Young players have energy, young players have enthusiasm, and I believe that the game of football is becoming a young man's game.

"I think that showed at the World Cup just past, and if you have young players with that type of energy and can play at a very high level for 90 minutes and that's what I expect tomorrow."

Arnold has also been hit by the loss of Mathew Leckie for Sunday's game in Al Ain, although the experienced midfielder could return for their second Group B clash against Palestine on Friday.

Australia, led by Jedinak and record scorer Cahill, won the Asian Cup for the first time in 2014 but Arnold said the victory in Sydney was ancient history -- as witnessed by his hair.

"You guys want to talk about four years ago? Believe it or not, four years ago I had black hair. That was a long time ago," the grizzled coach told reporters in Al Ain.

Brighton goalkeeper Mathew Ryan and QPR's Massimo Luongo, both 26, are among the veterans of 2014 along with versatile captain Mark Milligan, whose starting position remained under wraps a day before the Socceroos' opener.

Former South Sudanese refugee Awer Mabil, 23, and 25-year-old forward Jamie McLaren are among Australia's newcomers in a 23-man squad which has an average age of 26 and has 11 players with fewer than 10 caps.

"The depth of the team is there for all to see and I'm very excited about new faces that have come in and done extremely well for us. We're just raring to get going," said Milligan.

Arnold also said Australia's record against Jordan, which includes World Cup qualifying defeats in 2012 and 2015, both in Amman, had little bearing on Sunday's game.

"It was history that they beat us twice. Tomorrow has nothing to do with (that) -- it's all about the moment, it's all about ourselves growing as a team and putting in a great performance, and I expect that performance tomorrow," he said.

"The boys have got so much energy, they've got a lot of belief. We believe in ourselves, we believe in what we're doing and I expect them to win the game tomorrow."