The Socceroos are finding more curveballs than they expected at their pre-World Cup training camp.

New Adidas balls to be used during the World Cup combined with training at altitude has led to Socceroos being bamboozled by some unexpected trajectories.

Cooler than normal temperatures on Sunday led to balls wickedly dipping and swerving during a training match.

But as well as the lightweight ball's unexpected flight paths confusing goalkeepers and defenders, it's also proving a challenge for the Socceroo most reliant on his aerial ability - giant striker Josh Kennedy.

Headers are the 194cm striker's stock-in-trade - something he admits is proving more a headache with the new match balls at 1700 metres above sea level.

"It's difficult. You anticipate it's going to come to you and then it moves away from you," Kennedy told AAP.

"In that sense it's hard to judge things. You need to keep your eye on things.

"It's good we've got two weeks here and we can see how it moves and get used to it."

It's also a learning curve for defenders like Mark Milligan and Michael Beauchamp.

"Once the ball's in the air you're not sure what it's going to do," Milligan said.

"You saw today when balls went in behind, they kept floating and they dip and swerve - it's always something different.

"They're tough to adjust to."

And Beauchamp said: "They seem to get caught up somewhere up there. You think they're coming to you and they move at the last second."

While the Socceroos have combined their honesty with diplomacy, players from other World Cup teams haven't held back when asked about the new balls.

"It looks like it comes from a grocery store," said Brazilian goalkeeper Julio Cesar.

And Chilean goalkeeper Claudio Bravo called it "a beach ball".

Socceroos midfielder Jason Culina said he far preferred the Nike footballs usually used by the Australians, though he felt the best tactic with the Adidas version may be not to resort to the long ball too often.

"Play the short passes, keep the ball within the team rather than play the long ball. It's something we're getting used to," he said.

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