World number one Dinara Safina took a first step towards a second consecutive claycourt title by battling to a 6-3, 7-6 victory over Li Na at the Madrid Open on Wednesday.
Russian Safina, who had a first-round bye, had to work hard to subdue the gutsy Chinese and set up a third-round clash with unseeded Czech Lucie Safarova.
Safina won the Italian Open in Rome last weekend.
Russians Elena Dementieva and Svetlana Kuznetsova were beaten in Madrid.
Third seed Dementieva slipped to a 1-6 ,6-4, 6-2 third-round defeat by former world number one Amelie Mauresmo and sixth-seeded Kuznetsova lost 6-3, 6-2 to Ukrainian Alona Bondarenko in the second round.
Frenchwoman Mauresmo was joined in the last eight by Swiss Patty Schnyder, who ousted eighth seed Nadia Petrova 6-4, 6-7, 7-6.
Russian qualifier Vera Dushevina also reached the quarter-finals with a 6-3, 4-6, 6-2 win over Italy's Francesca Schiavone.
Belarussian Victoria Azarenka, 19, chasing her fourth WTA Tour title of the year, beat Peng Shuai of China 6-4, 6-1 in the second round.
The seventh seed, who has won in Brisbane, Memphis and Miami, broke serve six times and will play Hungarian Agnes Szavay on Thursday for a place in the quarter-finals.
Second seed Serena Williams retired from her first-round match against Schiavone on Monday with a knee injury and her sister Venus lost to Russian teenager Alisa Kleybanova in the second round on Tuesday.
