DOHA, Qatar (AP):

After months of debate about who is more deserving of the No. 1 ranking, Serena Williams and Dinara Safina can settle the issue on the court at the WTA's season-ending Sony Ericsson Championships.

Safina recaptured the top ranking from Williams yesterday, but the margin is so slim that the player who performs better at this week's tournament in Doha will end the year as No. 1 - adding an extra element of prestige to the lucrative event.

Safina has held the top spot for 26 weeks this year but the Russian has faced persistent questions about whether she's worthy of the title without having won a Grand Slam tournament.

Williams won her 11th major title at this year's Wimbledon after also taking the Australian Open.

"It would be awesome," Williams said yesterday about the prospect of ending 2009 atop the rankings. "It would be really cool. But I would have to win."

Actually, she only has to win one more match than Safina. If both players have equal results, Safina keeps the top ranking.

The eight-player tournament starts today with a round-robin group stage, with the top-two players from each group advancing to the semi-finals.

Different groups

Williams and Safina are in different groups, meaning they will not get to face each other until a potential match in the knockout rounds.

Williams was drawn with her sister Venus and Russians Svetlana Kuznetsova and Elena Dementieva.

The other group consists of Safina, former No. 1 Jelena Jankovic of Serbia, Victoria Azarenka of Belarus and Danish teenager Caroline Wozniacki.

"I'm in a tough part of the section of the draw," Serena Williams said. "So we'll see what happens."

Safina, meanwhile, is tired of defending her credentials as the top-ranked player in the world.

"I don't want to think about this right now," she said. "Last year, I was winning every tournament and they (were) asking me why I'm not No. 1. This year I became No. 1, there is no Grand Slam. It is every day going to be something."

Safina has 7,731 points in the latest rankings to lead Serena Williams by 155 points. Each win in the round-robin stage here is worth 160 points.

The other six players also have plenty to play for.

The total prize pool is $4.55 million and the champion receives $1.55 million if she completes the tournament undefeated - with $100,000 knocked off for each loss in the round-robin stage.

Venus Williams is the defending champion, while Azarenka and Wozniacki are competing in the event for the first time.