Less than a week before the World Cup kicks off, Socceroos goalkeeper Mark Schwarzer is still having problems reading the erratic flight of FIFA's controversial match balls.

The unpredictable balls, especially in Johannesburg's high altitude, are actually changing the game, according to coach Pim Verbeek.

Schwarzer and Verbeek aren't the first to criticise the Jabulani balls, and they won't be the last.

Many of the 32 teams preparing for the World Cup are having similar difficulties.

Outfield players have joined the chorus of discontent, but the issue affects goalkeepers more acutely than anyone else.

One bizarre bend, dip or swerve could mean a life-or-death mistake for the men between the posts.

"It doesn't have a real genuine flight, it's quite unpredictable" Schwarzer said as the Australians wound up their initial training camp in suburban Johannesburg and headed for a more remote wildlife lodge.

Asked if he was getting any better at reading the movement of the ball after more than a week's training in South Africa, he admitted: "Not really, no."

"By all accounts being at altitude with any ball is always difficult," he said.

"It makes the ball do different things.

"The ball has a mind of its own.

"This one seems to have more of a mind of its own."

Schwarzer said there was no point complaining about it.

"The ball is how it is, and we've just got to get on with it," he said.

"We are all in the same boat, we all have to deal with it.

"There's nothing we can do about that.

"We've just got to play, simple. There's no point going on about it."

Verbeek is blunt about the effect of the balls at altitude.

"It's changed the game, that's clear," he said.

Verbeek has concerns about how well the Socceroos are coping with it.

The defenders, for example, have been devoting time in practice to hitting long balls to each other.

"The curly balls are so difficult, he said.

"Balls over the top have to be very, very accurate.

"They have to be hit at the right pace or they won't stop.

"We have to get used to it, we still have to work on it, that's true.

"I am not 100 per cent satisfied.

"We have a week left (before Australia's first match against Germany in Durban)."

The Australians are trying everything to overcome the problem.

Schwarzer at times has been wearing sunglasses with a built-in camera during training, so that he and technical staff can analyse on film how the ball is behaving.

He joked that the glasses were a high-tech present from the head of NASA, then said: "No, there's no secret technology.

"There's nothing but a camera inside the sunglasses.

"It's just a camera to see what the perspective is from my view of the ball, that's all."

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