Rafael Nadal

Rafael Nadal retained the world number one ranking in men's tennis in the latest Association of Tennis Professional (ATP) list issued Monday but is under threat of losing it to Roger Federer as Wimbledon gets underway.

Nadal leads the way with 12,735 points from Federer (10,620) and Briton Andy Murray (9,230), but has pulled out of the grass court Grand Slam due to knee problems.

As a result, the title holder Nadal will lose 2,000 points in the next rankings issued in a fortnight. The rankings take results of 52 weeks into account.

If Federer gets a sixth Wimbledon crown July 5 he will be back on top 11 months after being dethroned by Nadal, improving his points tally by 600 points (losing 1,400 points as 2008 runner-up, but earning 2,000 as champion 2009).

ATP top 10 as of June 22 (previous ranking in parenthesis):

1. (1) Rafael Nadal, Spain, 12,735 points

2. (2) Roger Federer, Switzerland, 10,620

3. (3) Andy Murray, Britain, 9,230

4. (4) Novak Djokovic, Serbia, 7,860

5. (5) Juan Martin del Potro, Argentina, 5,730

6. (6) Andy Roddick, United States, 4,310

7. (7) Gilles Simon, France, 3,970

8. (8) Fernando Verdasco, Spain, 3,620

9. (9) Jo-Wilfried Tsonga, France, 3510

10. (10) Fernando Gonzalez, Chile, 3,165