BERLIN: Dinara Safina celebrates her 23rd birthday on Monday determined to prove she deserves to be world number one despite never having won a Grand Slam title.

The Russian takes to the clay courts of Stuttgart for the first time since her controversial elevation to the top of the rankings where she displaced Serena Williams, the holder of 10 Grand Slam crowns.

"There's no question that while I am very proud of my results over the past year, I would have liked to reach this achievement in a different manner," said Safina, the runner-up to Williams at the Australian Open this year.

"I hope to prove to everyone over the coming months that I merit the honour of being world number one."

Serena has made no secret at her puzzlement over the way the rankings operate.

"Well, she's really a good girl and she is a nice person. I just have the utmost respect for not only her, but everyone on this tour," said the American.

"I just think it's crazy that I can be so consistent throughout the year and last year and barely be No. 1. I have won two of the last four Grand Slams and got to the finals of three of the last four.

"I can't compute it. It's just psycho."

The Porsche Grand Prix, which starts in Stuttgart on Monday, will also feature six other top ten players including Russian Olympic champion Elena Dementieva and 2008 tournament winner Jelena Jankovic from Serbia who will be competing for a total of 700,000 dollars prize money.

Belarus teenager Victoria Azarenka will be looking to prove her surprise defeat of Serena Williams in the final of the WTA Miami event was no fluke earlier this month.

With the French Open starting on May 24, the Stuttgart tournament is a good chance for the world's top stars to work on their claycourt game as the surface has been imported from France and is the same used at Roland Garros.

"The players will have the ideal preparation for the French Open in Paris. We’ve got the same kind of clay and the same court dimensions as at Roland Garros," said tournament director Markus Guenthardt.

In contrast to a normal clay court, which has is approximately 60cm deep and made of a wide variety of materials, the clay in Stuttgart new court is only 2.5cm thick.

After the tournament, the three clay courts will be removed and disposed of by being used in road construction.