MELBOURNE, May 25 (Reuters) - Australia need to toughen up before next month's World Cup if they are to achieve their full potential in Germany, coach Guus Hiddink said on Thursday.
The Socceroos looked an efficient unit for long stretches of a 1-0 friendly victory against European champions Greece at the Melbourne Cricket Ground although Hiddink was not satisfied.
"I would say 70 percent of our play was excellent but it's the rest we need to focus on improving," the Dutchman told reporters.
"I'm not concerned but it's very easy to say 'We've beaten the European champions'.
"We need to put in the training and focus on improvement because games at World Cup level are decided on details.
"We also have to get more physical strength because three games in such a short time will be difficult."
Hiddink, who led the Netherlands and South Korea to World Cup semi-finals, said Australia had adapted well to the tactics he had imposed during three days of training before the game.
Australia started with a 4-3-4 formation on Thursday which had Blackburn's Brett Emerton in an unfamiliar right-back role and matchwinner Josip Skoko pulling the strings in midfield.
"The team knows exactly what position they should be in and what to do. I can shuffle players around and that is nice. But the foundation must be physical strength and that is something we need to work on," Hiddink said.
"The first half was good but the second we lost focus which is a worry. We gave away possession too easily.
"I'm not forgetting the good bits but you have to improve these areas if you want to be competitive."
Australia, who reached their first finals since 1974 when they pipped Uruguay in a penalty shootout in November, face Japan in their opening Group F match in Kaiserslautern on June 12.
"It was a good win but we are going to have to be tougher when we play Japan."