The new ball for 2010 World Cup will make more trouble for goalkeepers as it will be faster and more erratic than its predecessors, an Australian scientist said on Tuesday.

The ball, which was named Jabulani ("to celebrate" in Zulu), are complained by players that it behaves erratically and they are having difficulty judging its trajectory.

England goalkeeper David James has described new Adidas ball as "horrible", Spain's Iker Casillas says it is "rotten" and Gianluigi Buffon of Italy fears its "unpredictability" could ruin the World Cup.

Research by Adelaide University's Derek Leinweber would appear to back up complaints.

Professor Leinweber said the players had a point, with his computer simulations showing it was faster than previous balls, while its rough surface made it more erratic.

"And ... they bend better," he said. "What it means is that the goalkeeper's intuition is just a little bit off. You see the ball coming towards you, you might quickly work out where the ball is going to be, and something different happens."

Leinweber, who heads the university's chemistry and physics school, simulated trajectories for the almost perfectly spherical Jabulani which took into account the aerodynamic impact of the ball's unique tiny ridges.

"Any sort of texture on the ball, or grooves that are on the surface of the soccer ball, that has a big impact on the nature of the air flow," he said.