New world No. 1 Kim Clijsters crashed out of the US$1.3 million Canadian Open when she lost 1-6, 6-4, 6-1 to unseeded Russian Lina Krasnoroutskaya in the third round on Thursday.
But Clijsters's fellow Belgian, second seed Justine Henin-Hardenne, went through to the quarterfinals with a 6-3 7-5 victory over Russian Nadia Petrova.
Her defeat marked the first time Clijsters has failed to make the semi-finals of an event this season.
"I didn't have the best preparation coming into the tournament, but I decided to play and go for it and today I just didn't have the batteries in the second and third sets," she told reporters.
"After coming here from Los Angeles, and the jet lag, it was difficult. But she played very well in the second and third sets and she didn't make any mistakes," Clijsters said.
The Belgian, who took over the top spot from Serena Williams with her title triumph in Los Angeles last week, looked poised for an easy workout as she raced through the opening set in 19 minutes.
Playing in her fifth straight event, a tired Clijsters watched the match slip away in the second set behind a string of unforced errors.
Krasnoroutskaya, whose previous best performance was reaching the semifinals in Doha, kept up the pressure in the third set to secure a quarterfinal clash with Slovenia's Katarina Srebotnik.
"I'm very surprised," said 19-year-old Krasnoroutskaya, ranked No. 41 in the world.
"I didn't expect it from myself. I had nothing to lose. She's the No. 1 in the world and I just did it."
Amelie Mauresmo of France, the third seed and defending champion, advanced with a 6-4, 6-2 triumph over Fabiola Zuluaga of Colombia.
Mauresmo was joined in the last eight by a trio of Russians -- ninth seed Elena Dementieva, 10th seed Vera Zvonareva and 12th seed Elena Bovina -- and the unseeded Paola Suarez of Argentina.
Suarez upset fourth seed Daniela Hantuchova of Slovakia 6-2, 6-0 while Zvonareva put out eighth-seeded Yugoslav Jelena Dokic 6-3, 6-2.
Dementieva overcame fifth seed Anastasia Myskina of Russia 2-6, 6-1, 6-1 and Bovina notched a 6-2, 6-1 win over seventh-seeded South African Amanda Coetzer.