(CNN) -- Olympic champion Elena Dementieva became the latest seeded casualty at the Pan Pacific Open, going down 6-2 6-7 6-1 to Kateryna Bondarenko of Ukraine in the second round in Tokyo.
Third seed Dementieva served 11 double faults on her way to defeat at the Pan Pacific Open.
The third-seeded Russian, who was champion here in 2006, double-faulted twice on a break point and once on match point to lose to her 33rd-ranked opponent.
"There was nothing wrong with my serve. I was serving good today," Dementieva told reporters despite serving 11 double faults.
With the top two seeds, Dinara Safina and Venus Williams, both crashing out on Monday, Dementieva's exit left U.S. Open runner-up Caroline Wozniacki of Denmark as the top-seeded player remaining.
However, the fourth seed complained of illness during her match with Aleksandra Wozniak of Canada and pulled out when trailing 5-0 in the opening set.
Wozniacki said: "I've been sick all week and I haven't really practiced. I tried to play but it wasn't possible for me."
The remarkable run of results continued when sixth seed Vera Zvonareva was beaten 3-6 6-4 6-2 by fellow-Russian Alisa Kleybanova.
Former world number one Jelena Jankovic, seeded seven, is now the highest-ranked player still in the tournament, although she also struggled before beating Sabine Lisicki of Germany 6-3 4-6 6-2.
Crowd-favourite Maria Sharapova, the 2005 winner, is unseeded this year, but now appears favorite to win the tournament after crushing Australian Samantha Stosur 6-0 6-1 in just 57 minutes.
Sharapova, who is looking to claim her first WTA title since returning earlier this year from a lengthy lay-off due to a shoulder injury, told reporters: "I just try to improve as each tournament goes, playing one match at a time and focusing on the task ahead.
"When you don't play well you have to learn to get better. It's the first time I've had to make adjustments to my game and relearn the things that usually came so automatically."