AMELIA ISLAND, Florida (AFP) - Maria Sharapova survived a scare Thursday as she outlasted Anabel Medina Garrigues 7-6 (7/3), 5-7, 7-6 (7/1) to reach the quarter-finals of the WTA Amelia Island claycourt event.

Sharapova improved to 20-1 on the season but the Spaniard made her work for it.

She next faces 10th seeded Alona Bondarenko, who surprised Russian sixth seed Dinara Safina 7-6 (7/5), 0-6, 7-5 earlier in the day.

The top seeded Russian beauty is participating in her first tournament since losing to compatriot Svetlana Kuznetsova in the Indian Wells semi-finals.

American Lindsay Davenport also advanced on Thursday by beating Croatian qualifier Karolina Sprem, 6-4, 3-6, 6-4.

The 16th-seeded American converted 27-of-39 first-serve points to defeat Sprem in one hour, 49 minutes.

While Davenport was able to pull out a three-set victory, the same could not be said for second-seeded Anna Chakvetadze.

The 21-year-old Russian, who was seeking her second title of the year after claiming her seventh career championship at the Paris indoors event in February, fell to Dominika Cibulkova in Thursday's evening match.

The Slovakian won, 6-2, 3-6, 6-1, in a match that lasted 1 hour, 35 minutes.

Despite managing just one ace, Cibulkova emerged victorious due in part to her opponent's erratic serving. Chakvetadze recorded 11 double faults in falling to 4-5 this year.

Former champ Amelie Mauresmo of France reached the quarter-finals by beating Poland's Agnieszka Radwanska 3-6, 7-5, 7-6 (8/6) on Thursday.

The 28-year-old Frenchwoman, who won here in 2001, had been 0-4 against top 30 players this year prior to beating the 16th-ranked Pole.

Eighth seed Agnes Szavay of Hungary awaits the winner of the Davenport-Sprem match after posting a 3-6, 6-2, 6-3 win over Katarina Srebotnik.

Unseeded Alize Cornet and No. 13 Virginie Razzano also have advanced and will meet in an all-French quarterfinal.