Victoria Azarenka and Petra Kvitova were both winners on Friday to advance at the $5.535 million BNP Paribas Open.
The top-seeded Azarenka of Belarus had to overcome 12 double faults en route to a marathon 6-4, 6-7 (7-4), 7-6 (8-6) victory over Germany's Mona Barthel on the hardcourts at the Indian Wells Tennis Garden.
Azarenka improved perfect mark to 18-0 this season, including a trio of titles, by converting 6-of-8 break chances and saving 9-of-14 break opportunities by Barthel in the three-hour long match.
Kvitova had it much easier in her 6-1, 6-3 decision over fellow Czech Barbora Zahlavova Strycov. The third-seeded Kvitova reeled off three aces and was helped by her opponent's eight double faults to advance.
Upstart American wild card Jamie Hampton, a 22-year-old from Alabama, stunned 12th-seeded former world No. 1 Jelena Jankovic 6-4, 6-3, while 14th-seeded German Julia Goerges avoided an upset by whipping Brit Elena Baltacha 6-3, 6-2. The Serbian star Jankovic was the Indian Wells champion just two years ago.
Other seeded players who saw their tournament come to an end were 13th-seeded Russian Anastasia Pavlyuchenkova, who was ousted by American Vania King 6-4, 6-4, Slovakia's Daniela Hantuchova, the 19th seed, who dropped a 6-3, 6-7 (9-7), 3-6 decision to Czech Klara Zakopalova and 22nd-seeded Yanina Wickmayer of Belgium as she fell to Australia's Jarmila Gajdosova 2-6, 6-2, 6-4.
Also moving on to Saturday was Poland's Agnieszka Radwanska, the fifth seed, who defeated Romania's Sorana Cirstea 6-2, 6-4, eighth-seeded Li Na of China as she outlasted Galina Voskoboeva of Kazakhstan 3-6, 6-3, 6-3 and Russia's Vera Zvonareva, the ninth seed, who eased past Japan's Kimiko Date-Krumm 6-4, 6-4.
Rising American Christina McHale, seeded 32nd, reached the third round with a 6-3, 7-5 handling of Russian Elena Vesnina and 18th-seeded German Angelique Kerber moved on with a 2-6, 7-5, 6-4 decision over 18-year-old American Sloane Stephens.
Meanwhile, 31st-seeded Chinese Zheng Jie doused Dutch qualifier Michaella Krajicek 6-1, 6-3, 24th-seeded Anabel Medina Garrigues of Spain downed India's Sania Mirza 6-2, 7-5, Italian Flavia Pennetta, the 27th seed, defeated Spain's Carla Suarez Navarro 6-3, 6-4 and 25th-seeded Russian Svetlana Kuznetsova advanced past Timea Bacsinszky after the Swede retired in the second set while trailing 6-3, 2-0
The winner of this 12-day event will enjoy a $1 million windfall.