Amelie Mauresmo's [ Images ] bid to regain the world number one ranking took a knock when she lost 2-6, 6-2, 7-5 to Russian teenager Evgenia Linetskaya in the third round of the Pacific Life Open on Sunday.

In the men's tournament, top seed and defending champion Roger Federer [ Images ] began his campaign in the Masters Series event with a 6-3, 6-3 triumph over American Mardy Fish [ Images ].

Linetskaya saved a match point at 4-5 down in the third set when the second seed from France [ Images ] pushed a forehand volley wide.

Playing in swirling winds that dusted the court with sand in this desert community, Mauresmo then double faulted to allow the Russian to break serve and lead 6-5.

Linetskaya, who lost to Mauresmo at the Australian Open [ Images ] in January, clinched victory when she put away a volley.

The 18-year-old screamed in delight after registering her first win over a top-five player.

Mauresmo had a chance to regain the number one ranking from Lindsay Davenport [ Images ] here but is now in danger of losing her number two spot to Maria Sharapova [ Images ].

Mauresmo was not the only women's seed to fall.

Japan's [ Images ] Rika Fujiwara ousted number 24 Iveta Benesova [ Images ] of the Czech Republic 7-6, 7-6 and 17-year-old Russian Maria Kirilenko surprised number 28 Anabel Medina Garrigues of Spain 6-4, 6-4.

Fourth seed Elena Dementieva [ Images ] of Russia [ Images ] put out France's Severine Beltrame 5-7, 6-3, 7-6.

French Davis Cup hero Paul-Henri Mathieu upset 16th seed Tommy Haas [ Images ] of Germany [ Images ] 7-6, 6-3 in the men's draw.

Czech Tomas Berdych toppled number 19 Mario Ancic of Croatia [ Images ] 7-5, 3-6, 6-2 while another Czech, Jan Hernych, overcame number 20 Vincent Spadea of the U.S. 6-2, 1-6, 7-6.