Denmark’s Caroline Wozniacki holds aloft the World No 1 trophy in Beijing on Thursday. AFPThe 20-year-old dethroned American Serena Williams when Kvitova smacked a service return into the net.

A jubilant Wozniacki held her arms aloft in celebration as Tina Turner's hit "Simply the Best" blasted out of the PA system in Beijing's Olympic tennis centre.

The Dane become the 20th woman to top the standings since their inception in 1975. However, Wozniacki is the third player in the last two years to have reached the pinnacle of tennis without winning one of the four grand slam titles.

Meanwhile, Britain's Andy Murray struggled to find his rhythm before he dispatched Spaniard Albert Montanes 7-5, 6-3 to reach the quarterfinals in the men’s category.
World number 24 Montanes refused to get intimidated by the second seed and fought toe-to-toe for much of the first set before finally surrendering the break.

In Tokyo, World number one Rafael Nadal overpowered Canadian qualifier Milos Raonic 6-4, 6-4 to reach the quarterfinals of the Japan Open on Thursday. 

Second seed Andy Roddick remained on track for a final showdown with the Spaniard after repelling dangerous Frenchman Jeremy Chardy 6-4, 7-6.

Nadal broke through early in the first set with a whipped forehand return to take a 2-1 lead and continued to run Raonic ragged with some ferocious hitting from the baseline.
The second set followed a similar pattern as Nadal, much sharper than in his opening match and his semifinal defeat at last week's Thailand Open, turned the screw.

Serbia's Viktor Troicki bundled out fourth seed Juergen Melzer 7-6, 3-6, 7-6 of Austria.