A Josh Kennedy goal in the 71st minute secured yet another win for the Socceroos - who have still lost just twice in their past 21 internationals under Verbeek - in a match which was played 1700 metres above sea level on the outskirts of Johannesburg.

At times both sides appeared to have trouble coping with the official World Cup ball in their first South African hit-out under match conditions, with the ball flying everywhere at high altitude.

Australia's goal came from a high bounce following a deflected cross from Luke Wilkshire which fell perfectly for giant striker Kennedy to tap home after heading the ball down to himself.

Verbeek told Fox Sports after the match he is unsure if the World Cup balls will perform the same way in the Socceroos' first match in Group D against Germany, which will be played at sea level in the coastal city of Durban on June 13.

But with the other group games against Ghana and Serbia to be played at altitude, he said the Denmark game would prove a valuable experience for his team.

"It's not easy to play at altitude and you could see the balls are going much faster than we are used to," he said.

"You have to be more accurate with your passing and you have to change your game and we knew that of course but in training it's easier to do it than in a game so this was an interesting lesson I think.

"The ball is floating a lot more and we knew that of course but what you do for 25 years in your normal football life you can't change in a week but you have to change if you are playing at altitude."

Verbeek said the win mattered less to him than the fact his team kept another clean sheet - their 13th in their past 19 matches.

His squad is now also injury free, with the only major absentees against Denmark in Harry Kewell (groin) and Brett Emerton (calf) expected to be ready to face Germany in 12 days time.

As for his final 23, Verbeek has already announced that A-League goalkeeper Eugene Galekovic and youngsters Tommy Oar and James Holland won't be part of the squad.

The other two players expected to be cut are defender Shane Lowry and the final spot could come down to a battle between midfielders Dario Vidosic and Richard Garci.

Garcia missed the much of the EPL season with Hull City through injury and returned from knee surgery to play in the first half against Denmark, but did little to impress.

Verbeek added: "I have more or less made up my mind but I want to speak to the players first."