Last year's French Open winner Francesca Schiavone of Italy hit a stumbling block in her preparation for her title defence at Roland Garros this year in the form of American player Bethanie Mattek-Sands.
Mattek-sands put the third seed out of the tournament here in Madrid in straight sets, winning 7-6(7-5) 6-3 in one hour and 34 minutes.
The American applied constant pressure to the Schiavone serve, holding 10 break points throughout the match. Schiavone defended well, losing just one of them but it was a crucial break in the second that enabled the American to go on to victory and into the quarter-finals.
Australian Samantha Stosur who lost to Schiavone in last year's French Open final did no better - losing in straight sets 7-6(7-4) 6-3) to Anastasia Pavlyuchenko of Russia.
Stosur's compatriot Jarmila Gajdosova joined her in leaving the tournament after Lucie Safarova of the Czech Republic put paid to hopes of an Australian representative in the quarters - Safarova won comfortably 6-3 6-3.
There were no such problems for fourth seed Victoria Azarenka who powered her way past a bewildered Antonia Parra Santonja for the loss of just three games, 6-0 6-3.
China's Li Na is also in the quarter-finals after a three set battle with last week's Barcelona Open champion Roberta Vinci of Italy. Li Na won in one hour and 33 minutes and will play Schiavone's conqueror Mattek-Sands for a place in the semi-finals.
