World Cup ball 'unpredictable'

Its design is unlike any seen on a football pitch before - presenting a serious challenge to goalkeepers.

It's the ball that's got goal keepers complaining - and so-called soccer scientist Derek Leinweber isn't surprised.

“People will be looking for perhaps erratic movement on this ball - if you have a knuckleball kick it might swerve to the right could come back to the left, up and down and it's still going to be moving fast when it arrives at the goalkeeper,” Adelaide University head of Physics Prof Derek Leinweber said.

The Adelaide University professor is an aerodynamics expert who has previously modelled the behaviour cricket and golf balls and is now exploring the physics behind the Jabulani.

"What's surprising here is from the top of the arc the amount of bending that carries on - that could really surprise a goal keeper - we're looking at the order or easily a metre more bending in those last few metres," Mr Leinweber told SBS.

Players are putting the computer theories to the test.

The Jabulani is not just groovy by name - it is actually groovy by design, and that is what is responsible for its radically different performance.

Unlike the ultra smooth teamgeist ball designed for the last World Cup, the Jabulani's grooves and ridges create turbulence which traps air close to the ball, reducing drag.

“They'll also be able to bend this ball really well because the air is going to stay next to the all, it means the ball will respond more to any spin that's put on it so players that are good a putting a bit of spin on the ball have a really good chance of surprising the crowd," Mr Leinweber said.

“It's a little bit harder, it seems to come a bit quicker and then when it hits you it hits a bit harder” goalkeeper Peter Morris said.

The ball's bend-ability will likely make it popular with backyard players- with even the most average able to pull surprising moves.