Sep 29, 2008, 21:00 GMT
Stuttgart - Serena Williams aims to close the year on a high but the American's world number one ranking is under threat from Jelena Jankovic and others in the final weeks of the season.
Williams, 27, is playing her first event in Stuttgart at the star-studded Porsche Grand Prix, which started on Monday, since winning the US Open last month.
'The US Open is not the end of the year,' the top seeded Williams told reporters on Monday.
'I hope to do well in the last tournaments of the year,' said the nine-time Grand Slam champion.
Williams, will have to be at her best as the race for the year-ending number one is still wide open. The Serb Jankovic trails by just 21 points, and Russians Dinara Safina and Elena Dementieva are also in the frame.
Like Williams, the challenging trio has a first-round bye in the elite Stuttgart field, where eight of the top 10 players have gathered for a top prize of either a Porsche 911 sports car or 100,000 dollars.
Williams will start play in Stuttgart against China's Li Na, who routed Czech Nicole Vaidisova 6-1, 6-2 in the tournament opener.
Alona Bondarenko of Ukraine defeated Greece's Eleni Daniilidou 7-6 (7-5), 6-1 to set up a match with Jankovic and the Olympic champ Demetieva plays Austrian Sybille Bammer, who saved two match points in a 4-6, 6-2, 7-5 comeback win over German wildcard Tatjana Malek.
Jankovic was due to arrive from Beijing where the China Open title on the weekend boosted her morale in the final season grind.
'I'm close to gaining the number one spot again, but I'm just trying to focus on playing one match at a time and working on my game. I would love to come back to number one and end the year at number one,' said Jankovic in China.
Dementieva also has fond memories of Beijing as the Olympic gold in August was the fulfilment of her biggest dream in tennis.
'There is nothing bigger than the Olympics, nothing can top that Olympic medal,' the 26-year-old said on Monday.
'But there is still a lot to achieve ... I am still thinking of the number one,' she added.
Dementieva beat Venus Williams for the Olympic title, with Wimbledon champion Venus also in Stuttgart in a rare showing of both Williams' outside the majors. Both are in opposite halves of the draw and can not meet until the final.
Serena and Venus were playing doubles together for the first time since teaming up for Olympic gold last month, defeating Slovakia's Daniela Hantuchova and Agnes Szavay of Hungary 6-4, 6-1 on onday.
'We just both wanted to be here. So we might as well play doubles,' said Serena Williams.
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