The Adidas 'Teamgeist' soccer ball has just 14 panels - with fewer seams - making its surface 'smoother' than conventional soccer balls which have a 26 or 32 panel hexagon-based pattern.

This makes it aerodynamically closer to a baseball and, when hit with a slow spin, will make the ball less stable, giving it a more unpredictable trajectory in flight.

"With a very low spin rate, which occasionally happens in soccer, the panel pattern can have a big influence on the trajectory of the ball and make it more unpredictable for a goalkeeper," said Dr Ken Bray, a sports scientist at the University of Bath and author of the new popular science book How to score ?science and the beautiful game.

"Because the Teamgeist ball has just 14 panels it is aerodynamically more similar to the baseball which only has two panels.

"In baseball, pitchers often throw a 'curve ball' which is similar to a swerving free kick and the rotating seam disrupts the air flow around the ball in much the same way as a soccer ball does.

"Occasionally though, pitchers will throw a 'knuckleball' which bobs about randomly in flight and is very disconcerting for batters.

"It happens because pitchers throw the ball with very little spin and as the ball rotates lazily in the air, the seam disrupts the air flow around the ball at certain points on the surface, causing an unpredictable deflection.

"With the world's best players in Germany this summer, there are bound to be plenty of spectacular scoring free kicks.

"But watch the slow motion replays to spot the rare occasions where the ball produces little or no rotation and where goalkeepers will frantically attempt to keep up with the ball's chaotic flight path."

The ball, which has been used by teams competing in the World Cup in practice sessions, has already been criticised by England goalkeeper Paul Robinson and Germany goalkeeper Jens Lehmann for its light-weight and unpredictable behaviour.