BIRMINGHAM, UK - Many players had to do double duty at the AEGON Classic on Thursday to catch up matches delayed by rain over the past few days. But while the top four seeds remain in the title hunt, defending champion Magdalena Rybarikova's grip of the trophy was pried loose by qualifier Sesil Karatantcheva.

Among those to win twice was No.2 seed Maria Sharapova, who led Bethanie Mattek-Sands 4-0 when their second round match was abandoned on Wednesday, and barely raised a sweat in completing the job today, 60 63. Later in the day the 2004 and 2005 champion was back on court, booking her place in the quarterfinals with a comprehensive 63 61 defeat of fellow Russian Alla Kudryavtseva.

Third seed Yanina Wickmayer, who was runner-up here two years ago, trailed British wildcard Laura Robson 3-1 in the second set of their second round match. But the powerful Belgian handled the damp conditions the better, staying the course for a 75 64 win. Her berth in the last eight was duly secured with a straight sets defeat of No.14 seed Tamarine Tanasugarn, 64 64.

Three other players secured places in the last eight. Aravane Rezai, seeded fourth, finished off against Anastasia Rodionova and then backed up to end the run of qualifier Mirjana Lucic, 75 63; having upset ninth seed Aleksandra Wozniak, 192nd-ranked qualifier Alison Riske beat Anna Chakvetadze in three sets; and Karatantcheva, also a qualifier, beat Rybarikova, 62 67(3) 62.

But although she got past Anne Keothavong earlier in the day, top seed Li Na's third round match against No.13 seed Angelique Kerber was suspended due to darkness at a set apiece; fifth seed Sara Errani is up a set against Marina Erakovic; and qualifier Kaia Kanepi is up a break in the first set against Michelle Larcher de Brito.

The quarterfinals that are set will see Sharapova play Karatantcheva, and Riske to face Wickmayer.