Venue: Melbourne Park Date: 18-31 January
Coverage: Live on BBC Red Button (streamed on BBC website) and Radio 5 Live sports extra daily from 0830 GMT, text commentary daily from 0000 GMT on BBC Sport website
Williams is using Sydney as her only Australian Open warm-up
Serena Williams and Dinara Safina won their opening matches of the new season in very different style at the Sydney International.
Williams, the world number one, thrashed Maria Jose Martinez Sanchez 6-1 6-2 to reach the quarter-finals.
Former number one Safina lost the opening five games against Agnieszka Radwanska before winning 7-5 6-4 in the Russian's fist match since October.
Third seed Svetlana Kuznetsova lost 7-5 6-2 to Slovakia's Dominika Cibulkova.
"Definitely I'm very worried about the match today, and I have to improve and practice a lot before Australian Open but that's not the worst thing in the world," said Kuznetsova.
If you start to cry in the first game of first match, then what can happen when it's going to be the end of the season?
The French Open champion follows fellow seeds Caroline Wozniacki, Jelena Jankovic and Vera Zvonareva in making an early exit in Sydney.
Williams spent just 72 minutes on court in her first competitive match of the year and said the fact that many of the leading names were already out meant little to her.
"I don't care who I play," said the American. "Whenever I play someone they play their best.
"I play Vera Dushevina next and she's a good player and she's been ranked high before. So whoever I play, believe me, they're going to play like number one on that particular day against me for whatever reason, so it doesn't matter for me."
Safina had not played since pulling out of the season-ending Tour Championships in October with a back injury that brought to an end an emotional 2009, during which she reached number one in the world but failed to back it up with a first Grand Slam title.
The Russian needed one hour, 47 minutes to see off Radwanska, reeling off nine straight games after initially dropping 5-0 behind.
"It's the first match of the year," stated Safina. "If you start to cry in the first game of the first match, then what can happen when it's going to be the end of the season?
"It was 20 minutes and 5-0. I thought, 'OK, at least try to stay a little bit longer on the court'."
Sixth seed Victoria Azarenka of Belarus beat Japanese veteran Kimiko Date Krumm 6-1 5-7 7-5, while France's Aravane Rezai defeated Hungarian Agnes Szavay - conqueror of Jankovic on Monday - 6-3 7-6 (7-5).