American Andy Roddick took over as world number one today when he beat Tommy Robredo of Spain 6-3 6-4 in the last 16 of the Paris Masters.
He is the 22nd player to be top of the rankings since they were introduced in 1973 and the sixth American-born player.
Spain's Juan Carlos Ferrero, number one since September, was beaten by Czech Jiri Novak 7-5 7-5 earlier today.
After this tournament, the two men travel to Houston for the season-ending Masters Cup where the year-end number one will be crowned.
Roddick can put clear water between himself and Ferrero by winning in Paris, the last tournament of the regular season.
