DUBAI, United Arab Emirates (AP) -- Former U.S. Open champion Samantha Stosur lost to doubles specialist Roberta Vinci of Italy 6-2, 6-4 Thursday in the quarterfinals of the Dubai Championships.
Stosur's loss follows a quarterfinal exit in Doha last week as well as a second-round defeat at the Australian Open.
Stosur had 28 unforced errors and was broken twice in each set. Her first serve percentage was only 58 percent in the second set and she faced eight break points.
"Way too many errors," Stosur said. "She did well to not be bothered by anything I was trying to do. She used her slice very well, which kept all the points neutral. I made way too many mistakes on those neutral balls."
Despite the latest setback, the 28-year-old Australian said she felt she was improving over her dismal start to the year.
"January didn't really go as well as I wanted it to. I wasn't playing up to the standard and level that I think I'm capable of," she said. "The last couple of weeks, it's gotten better. I've played many more good matches than bad, so it's certainly on the way up."
Vinci will face doubles partner Sara Errani in the semifinals. The seventh-ranked Italian beat 12th-ranked Nadia Petrova of Russia 6-4, 0-6, 6-3.
"I spoke with my coach to play more aggressive," said Vinci, who beat sixth-ranked Angelique Kerber to reach the quarterfinals. "I played a lot on her backhand. She has an unbelievable forehand. So on my mind, I try to play against her backhand because she has a lot of problem with backhand, and try to change some slice and also some top when I have time."
Vinci said her recent success in doubles -- the Italian has 19 doubles titles and seven singles -- has contributed to her resurgence in singles, where she is ranked 17th.
"Probably in doubles, you can try also something that you can play in singles," Vinci said. "I probably play more relaxed and then I play better in the singles."