By the start of the 21st century tennis had become a multi-billion pound industry and one of the most widely played sports in the world.

The International Tennis Federation which governs the game has 198 National Associations - more than most international sporting federations.

Member nations include countries from every continent such as Australia, Brazil, China, France and Mali.

The professional tour has four major tournaments; the Australian Open which starts in January, the French Open which starts in May, Wimbledon which starts in June and the US Open which starts in August.

Top male players can earn up to $4m a year on the men's ATP Tour.

Women's tennis is also big business - America's Venus Williams earnt $2.5m in prize money alone in 2001 competing on the WTA Tour.

The best players can also compete for their countries in the Davis Cup for men and Fed Cup for women.

Davis cup was named after American tennis player Dwight Filley Davis and was first played between the USA and Great Britain in 1900.

The Fed Cup began in 1963 to celebrate the 50th anniversary of the ITF.

Both are now global competitions involving nearly 140 countries for Davis Cup and nearly 100 for Fed Cup.