Second-seeded Amelie Mauresmo won only two games Thursday, losing 6-2, 6-0 to Slovenia's Katarina Srebotnik in the second round of the Zurich Open.
It took Srebotnik 54 minutes to break her opponent five times, with Mauresmo winning 17 percent of her second-serve points.
The Frenchwoman was also knocked out in her first match in Moscow last week.
Top-seeded Lindsay Davenport rallied to beat Daniela Hantuchova of Slovakia 3-6, 7-5, 6-2. The American will now move to No. 1, up from No. 3, in the rankings.
Italy's Flavia Pennetta also advanced to the quarterfinals after beating Bulgaria's Sesil Karatantcheva 5-7, 6-1, 6-3, AP reports.
Rescuers found the pilot of one of the two Su-34 fighters that had collided in midair in the Far East on January 18