Novak Djokovic a threat to Roger Federer hitting 300 weeks as world number one

ROGER FEDERER: The Swiss aims to make it 300 weeks on top of the rankings (Getty Images)

Roger Federer races past milestones with the speed of some of the taxi drivers on the freeways here in China's largest city. The latest target in the sights of the 31-year-old Swiss is a record 300th week at the top of the world rankings, which he will achieve if he reaches at least the quarter-finals of this week's Shanghai Masters.

The man breathing down Federer's neck is Novak Djokovic, who arrived yesterday following his victory in the China Open in Beijing on Sunday. Djokovic needs to win the title next weekend to reclaim the No 1 spot, which Federer took from him by winning Wimbledon this summer.

Federer's feat in returning to the head of the world rankings, 14 months after he had been supplanted by Rafael Nadal, was arguably the greatest achievement of his career. However, he faces a huge challenge between now and the end of the season to hold off Djokovic.

Once this week is out of the way Federer will have to defend 3,000 of his current total of 11,805 ranking points in three successive weeks at the end of the season, having ended 2011 by winning his hometown tournament at Basle, the Paris Masters and the World Tour Finals in London.

Djokovic, in contrast, won just 560 in the same three tournaments last year after apparently running out of steam following his extraordinary efforts earlier in the campaign.

"That's the target," Djokovic said when asked about the world No 1 ranking. "It's still quite open and there are still tournaments to come, big ones."

Britain's Heather Watson, the world No 71, is hoping to improve her own ranking at the Japan Open in Osaka this week and made a good start when she beat Slovenia's Polona Hercog 6-4, 6-4 in the first round. Laura Robson was due to play her opening match today against Greece's Eleni Daniilidou.