Qualifying: Britain's Laura Robson went down 6-4, 7-6 to Michaella Krajicek and Naomi Cavaday lost 6-0, 6-1 to Yanina Wickmayer.
Katie O'Brien, however, has avoided the need to qualify by breaking into the world's top 100. If the world No 87 defeats Austria's Patricia Mayr (No 90) she could face Jelena Jankovic (No 8).
Sisters may meet
Serena Williams, the defending champion, could face her sister Venus in the semi-finals. Dinara Safina and Svetlana Kuznetsova are top seeds in a tougher bottom half of the draw, where Justine Henin's Grand Slam comeback could see her play fellow Belgian Kim Clijsters in the quarter-finals.
British pair in final
Sydney international Britain's Ross Hutchins and his Australian partner, Jordan Kerr, reached the doubles final at the Sydney International with a 7-5, 6-3 victory over Simon Aspelin and Paul Hanley. They were due to meet Daniel Nestor and Nenad Zimonjic in today's final.