Australian Jarmila Gajdosova retired hurt in her second-round match against Russian Nadia Petrova at the Estoril Open on Wednesday.
Gajdosova retired after losing the opening set 7-6 (7-2) with the seventh-seeded Russian advancing to the quarter-finals.
Meanwhile Swiss Stanislas Wawrinka made a winning debut at the Estoril Open, the third seed dishing out a 7-6 (7-5) 6-1 second-round defeat of Ivan Navarro at a rain-hit Estadio Nacional.
The 22nd-ranked Wawrinka, seeded behind Juan Martin Del Potro and Frenchman Richard Gasquet, needed one hour to get through the first set against a clay specialist ranked 232 and playing only his second ATP-level match of the season.
Wawrinka, twice a clay semi-finalist this season who reached the Monte Carlo quarters, battled in the first set on a day of blowing rain squalls and wind which lowered temperatures and made conditions heavy underfoot.
Wawrinka went down a break, 2-4 in the first set but got it straight back before winning a tiebreaker where Navarro saved four set points.
In the second set, the 27-year-old Swiss ran away with the victory in less than 90 minutes with six aces.
Qualifier Navarro had won a match nine years ago with the Swiss at the entry Futures level.
In 2009 Navarro also made it to the second round where he lost to American Mardy Fish.
In other women’s play, top seed Roberta Vinci of Italy dispatched Portuguese hope Maria Joao Koehler 6-2 6-0 but 2005 winner Zheng Jie of China, the fifth seed, lost 6-4 6-1 to Kazak Galina Voskoboeva.
Sixth seed Kaia Kanepi of Estonia put out the last American in the field by defeating Vania King 6-3 6-4.