Stosur last won a doubles title at Eastbourne (England) in 2007, with American Lisa Raymond. She's won two singles titles since though, and the 26-year-old Australian reached a career-best No. 5 world ranking on July 5. Playing in her first tournament since breaking into the Top 5, Stosur beat qualifier Christina McHale, 6-1, 7-5, in the second round of the Bank of the West Classic on Wednesday.
Stosur, the tournament's top seed, will meet seventh-seeded Yanina Wickmayer in Friday's quarterfinal at Stanford's Taube Family Tennis Stadium. Wickmayer beat Dominika Cibulkova, 6-1, 6-4, in the second round.
Russian Maria Kirilenko assured herself of her best finish at Stanford in three trips by beating sixth-seeded Shahar Peer of Israel, 6-4, 6-3, in Thursday's early match. Kirkilenko reached the second round in each of her two previous visits.
The 27th-ranked Kirkilenko continued her fine season by becoming the first to knock off a seeded player in the tournament. She's also had her career best results at the Australian Open (quarterfinals), French Open (fourth round) and Wimbledon (third round) this year.
Stosur, meanwhile, has 22 career doubles titles to her credit, and remains competitive, reaching eight finals (including Wimbledon and the U.S. Open) and five semifinals with 2009 partner Renae Stubbs and current partner Nadia Petrova since last winning.
"It's not like I have changed anything dramatically overnight," said Stosur, who lost to eventual champion Marion Bartoli in the semifinals of last year's Bank of the West and lost to eventual champ Aleksandra Wozniak in 2008. "It's just a combination of everything that I have been doing over the past few years and now it's all coming together. But it is nice to walk into a tournament and be the No. 1 seed or top-five in the world. It's a good feeling and something I have wanted to get to my whole life."
Stosur lost her first-round match at Wimbledon last month and that's been about the only disappointment of the season. She won her second career title at Charleston earlier in the season, reached the finals of the French Open and the semifinals at Indian Wells and Eastbourne.
"Once you produce some good results, it instills more belief," Stosur said. "But I haven't changed anything in my game. I have still been working on the same things, just getting better at them. It has been important to staying consistent, week in and week out."
Stosur won her 36th match of the season, the most on the tour. She carries a career 302-107 mark into Friday's match against the 20-year-old Wickmayer, ranked No. 17.
"The high ranking feels good," Stosur said. "It was a goal for me to get to No. 10, and I was kind of close to reaching that even though it took me a few months. Once I got to that point, all of a sudden I moved up to No. 5. To have another big jump like that so soon is really pleasing. There definitely is a lot of hard work to be done in the future if I want to stay there or try and get better."
Second-seeded Elena Dementieva needed three sets to beat 39-year-old Kimiko Date Krumm, 3-6, 6-3, 6-4, on Wednesday night to reach the quarterfinals. She'll meet either No. 5 seed Maria Sharapova or Olga Govortsova.
"I think sometimes it is good to play three sets and go through some difficult moments like that," Dementieva said. "It was a good fight. Maybe I wasn't playing at my best, but I was fighting and trying to find a way to win. I am glad I could do it."
Dementieva played her first match since retiring in the semifinals of the French Open with a left calf injury. She missed her first Gram Slam event (Wimbledon) in 10 years, ending a run of 46 consecutive Grand Slam appearances.
"It's never easy to play after a layoff of two weeks without competition, so it took me awhile to get into the game," Dementieva said. "Kimiko was playing very hard and flat, and I can't remember the last time I played against someone with that style of game. We had never played before. It's pretty amazing how well she is playing and she is in great shape. She is very quick and knows how to use her speed, so I was trying to play deep enough and not go flat with her."
Date Krumm returned to the WTA Tour last year after a 12-year layoff. She was ranked as high as No. 4 in 1995.
Third-seeded Agnieszka Radwanska survived a tight first set to beat qualifier Olga Savchuk, 7-6 (7-4), 6-2, and reach the quarterfinals, where she will meet Kirilenko.
"It's always difficult during your first tournament on the hard court," Radwanska said. "I thought I was playing a lot better, maybe not so much in the beginning but my second serve was also better."
Bartoli, meanwhile, didn't waste much time extending her winning streak at the Bank of the West Classic.
The 14th-ranked Bartoli beat American Ashley Harkleroad, 6-1, 6-4, Tuesday. The fourth-seeded Frenchwoman beat Harkleroad for the first time in three meetings, though it was their first meeting in six years.
"She played really well, especially in the second set," Bartoli said. "For someone who hasn't played that much lately, she was giving me a hard time out there."
Bartoli, who faced wildcard Ana Ivanovic in the second round Thursday night, won 81 percent of her first serve points to overwhelm Harkleroad.
Fifth-seeded Maria Sharapova took care of business Tuesday night, dispatching China's Jie Zheng, 6-4, 7-5, before a record-setting session crowd of 3,580, just 216 less than capacity.
"I don't think I took enough advantage of her serve, especially her second serve," Sharapova said. "I could have done a better job."
Sharapova, in her second Bank of the West Classic, lost to Zheng in March at Indian Wells, the last time the players met. The 15th-ranked Russian was forced to the sidelines right after and missed six weeks with a right elbow injury.
"When you don't play for a while you have to be ready from the beginning," Sharapova said. "I wanted to adapt as quickly as I could."
Sharapova reached the quarterfinals of this event last year, losing to Venus Williams. Tuesday's win was the 15th in her past 18 matches.
American Melanie Oudin fought back from a 5-1 deficit in the second set to force a third set against Canadian Aleksandra Wozniak and won the match, 6-7 (6-8), 7-5, 6-3.
"I thought I was playing well the whole match," Oudin said. "I think when it got close she got a little tight and made a couple of mistakes. When I got down I had nothing to lose and I relaxed. When it got to 5-4 I thought 'I just won three in a row. I can win another one.' When it got to the third set it was anybody's game."
Former Stanford All-American and NCAA singles champion Lilia Osterloh and UCLA grad Riza Zalameda lost their second round doubles match to Sarah Borwell and California grad Raquel Kops-Jones, 4-6, 6-3, 10-6, Thursday morning to become the first to reach the semifinals.
Osterloh will be inducted into the Stanford Hall of Fame this fall.