Roddick quick as a rocket

His serve is akin to a category four hurricane, but Andy Roddick is capable of hitting a tennis ball even harder.

That is the verdict of a leading tennis expert who says the American is the best server in the game. Roddick broke his own world record with a 153mph piledriver at Queen's last month and could again threaten that mark in tomorrow's semi-final against Mario Ancic.

Alex Niepel, a head tennis coach at Leeds Metropolitan University's Carnegie sports academy, believes there are a combination of factors which explain his immense power.

She said: "Physically, he is very strong with superb upper body strength. Also his timing is unbelievable and he has excellent co-ordination, extending from the ground right through to hitting the ball. Roddick is outstanding in all three of these components which, allied to modern rackets and balls, produce a massive service. In every sport, at world-class level, records are constantly being broken so there is no reason why he shouldn't continue doing so."

Roddick's ace at Queen's represented the third time this year he has improved the world record. In February he hit 150mph and in April 152mph in the Davis Cup.

The serve is a major weapon in the No2 seed's armoury but does not make him unbeatable. As serving speeds have improved so have standards of returning.