World number one Dinara Safina [ Images ] took a first step towards a second consecutive claycourt title by battling to a 6-3, 7-6 victory over Li Na [ Images ] 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 [ Images ].

Safina won the Italian Open in Rome last weekend.

Russians Elena Dementieva [ Images ] and Svetlana Kuznetsova [ Images ] 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 [ Images ] 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 [ Images ], who ousted eighth seed Nadia Petrova [ Images ] 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 [ Images ] Francesca Schiavone.

Belarussian Victoria Azarenka [ Images ], 19, chasing her fourth WTA Tour title of the year, beat Peng Shuai [ Images ] of China 6-4, 6-1 in the second round.

The seventh seed, who has won in Brisbane [ Images ], Memphis and Miami [ Images ], broke serve six times and will play Hungarian Agnes Szavay [ Images ] on Thursday for a place in the quarter-finals.

Second seed Serena Williams [ Images ] 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.