Caroline Wozniacki's ascent to the world No 1 spot has reignited the debate over the way women's rankings are computed.
Wozniacki, 20, is having an impressive year. She has already won six singles titles in 2010, which is the best since Justine Henin's 10 in 2007, after winning last night's China Open final against Vera Zvonareva. She has also won a tour-leading 59 matches this year and has one loss in her last 25. The problem is she has yet to win a grand slam.
Her best at a major is the 2009 US Open final. This year, she reached the semi-finals at Flushing Meadows, the quarter-finals at the French Open and the fourth rounds at Wimbledon and the Australian Open. Does that make her a worthy replacement at the top of the rankings for Serena Williams, who has won the Australian Open and Wimbledon this year? Serena has been out with a foot injury since winning her 13th grand slam crown at Wimbledon, opening the door for Wozniacki.
The Dane becomes the third women in the past two years to reach the top ranking without winning a grand slam, after Dinara Safina and Jelena Jankovic. Under the present system, Serena has to defend the points she won in tournaments last year. Her inability to do so has seen her tally drop from 9,075 points at the start of the year to 6,855.
The argument is that a world No 1 should play more often than Serena, but on the other side of that coin, Williams has won both her matches against Wozniacki.