The story

There is a mathematical reason why the French Open is so different to any other of the Grand Slam tennis tournaments.

The Roland Garros tournament is currently being contested, with Rafael Nadal looking for his fifth win in a row, and world number two Roger Federer searching for his first ever French Open title. • Get the latest French Open news

What has brought problems to Federer, and to other greats like Pete Sampras and Boris Becker -- who never won a French Open, is the clay surface on which it is contested. Read full article »