Djokovic has world's top ranking in reach

(AP)

Only two men have topped the world rankings since Roger Federer went to No 1 by winning the 2004 Australian Open. Within the next few weeks, however, Novak Djokovic is likely to break the stranglehold that Federer and Rafael Nadal have held on the men's game for the past seven years.

Less than four months ago Nadal topped the rankings with a total of 12,390 points, almost double Djokovic's tally of 6,240. Since then, however, Djokovic has been on an extraordinary unbeaten run, winning tournaments in Melbourne, Dubai, Indian Wells, Miami and Belgrade. With 9,710 points in yesterday's updated list, the 23-year-old Serb is now just 2,205 behind Nadal.

Crucially, Djokovic has several chances to make up further ground on the Spaniard in the coming weeks. The rankings are based on a rolling points total going back over the previous 12 months and the world No 2 has several chances to improve on his haul from last year, when he had comparatively little success during the clay and grass-court seasons.

In contrast the best Nadal can do in four of his next five events – this week's Madrid Masters, next week's Rome Masters, the French Open and Wimbledon – is to defend the maximum points he earned with victories last year. He can improve his points total only at Queen's Club, where he reached the quarter-finals last June.

Although there is little sign of an end to Nadal's domination on clay, the world No 1 having not lost on his favourite surface since the 2009 French Open, he can expect a major challenge from Djokovic over the next five weeks. The Serb has played well on clay in the past and opened his latest campaign on the surface with victory in Belgrade at the weekend

Madrid is the first clay-court event of the year in which the top two players have both competed. Nadal looks to have the tougher draw, facing Marcos Baghdatis in the second round and could then meet a rejuvenated Juan Martin del Potro in the third and Jurgen Melzer in the quarter-finals.

If results go to form Djokovic's first major test will not come until the quarter-finals against David Ferrer. In the semi-finals he is seeded to meet Andy Murray, who will play his first match tomorrow against the winner of today's first-round meeting between Ivan Ljubicic and Gilles Simon.

At the top of the women's rankings Caroline Wozniacki appears to be under little threat, especially as Kim Clijsters, the world No 2, is not playing in Madrid and is also expected to miss Rome. The Belgian is nursing an ankle injury she sustained while dancing at her cousin's recent wedding. Vera Zvonareva, the world No 3, was taken to three sets for the second round in succession yesterday before beating Elena Vesnina, 0-6, 6-3, 6-3.

Elena Baltacha, the British No 1, recorded her first victory of the clay-court season by beating Jill Craybas 6-4, 1-6, 6-2 in the opening round of the ITF event at Cagnes-sur-Mer in France. "Clay is a challenge for me but I put in some hard work in at the La Manga club in Spain before I started playing tournaments and it's great to see it paying off," Baltacha said.