TOKYO - Defending champion Samantha Stosur reached the quarter-finals of the Japan Women's Open on Thursday after fellow Australian Jarmila Gajdosova retired with an ankle injury at the start of the second set.
Samantha Stosur of Australia hits a return during the women's singles semi-final match at the China Open tennis tournament in Beijing on October 4, 2014
The big-serving Stosur, the 2011 US Open champion, took the first set on a tieback 7-6 before her opponent pulled up after losing the first game of the second set.
Top seed Stosur, a former top five player, will play Yulia Putintseva of Kazakhstan in the last eight of the $250,000 event in Osaka.
American Lauren Davis thrashed Japanese qualifier Shuko Aoyama 6-1, 6-1 while Zarina Diyas of Kazakhstan overpowered Spain's Lara Arruabarrena 6-0, 6-1.
Croatia's Ana Konjuh beat fourth-seeded Coco Vandeweghe of the United States 6-2, 3-6, 6-3 in the day's tightest match.