Top-seeded Maria Sharapova struggled past Michaella Krajicek at Los Angeles on Thursday to become one of four Russians to book quarterfinal berths at this 600,000-dollar US Open tuneup.
Sharapova, winner of the tier one title in San Diego on Sunday, clawed her way to a 7-6 (7/4), 6-7 (3/7), 6-4 third-round victory over her unseeded Dutch opponent.
After they split the first two sets, Krajicek gained the upper hand with a break to lead 4-3 in the third.
Sharapova battled back to break in the next game to put the set back on serve.
Sharapova faced a break point again in the next game, but the defending US Open champion rallied to hold.
After fending off two match points, Krajicek finally was broken to close the match, which lasted 2 hours, 48 minutes.
Krajicek fell to 0-3 lifetime against Sharapova, who will face compatriot Elena Dementieva in the quarterfinals.
Dementieva, the ninth seed and defending champion advanced on Thursday when No. 5 Daniela Hantuchova retired in the second set of their third-round match due to an upper-respiratory illness.
Dementieva held a commanding 6-3, 4-1 advantage when her Slovakian opponent conceded. The 25-year-old Russian, who improved to 8-3 against Hantuchova, has yet to lose a set in three matches at this tournament and owns an eight-match winning streak here dating back to last year.
While Sharapova leads the all-time series with Dementieva, 6-2, she lost their semifinal meeting at Los Angeles a year ago.
Fourth-seeded Russian Nadia Petrova won the day's first match with a 6-1, 6-2 victory against Slovakian Katarina Srebotnik.
Petrova won 33-of-42 first-serve points and blasted 10 aces en route to her fifth consecutive win against the 26-year-old.
France's Virginie Razzano is Petrova's quarterfinals foe after defeating Sania Mirza of India, 6-1, 7-6 (10/8).
Petrova won her only previous meeting with Razzano, who is ranked 52nd in the world and seeking her first WTA singles title.
Unseeded Russian Maria Kirilenko also advanced with a 6-3, 6-4 triumph over Gisela Dulko or Argentina.
Kirilenko, 20, set up a quarterfinal clash with third-seeded Serbian Ana Ivanovic, a 6-2, 6-2 winner over Czech Lucie Safarova.
Second-seeded Serbian Jelena Jankovic also booked her quarterfinal berth, defeating Austrian Sybille Bammer 6-2, 6-1. She'll face Victoria Azarenko of Belarus, a 6-1, 6-2 winner over Ukrainian Kateryna Bondarenko.