No problems for Na

Second seed Li Na eased into round two of the Madrid Open as she overcame Kirsten Flipkens of Belgium in straight sets.

Australian Open champion Na fell at the first hurdle in the Spanish capital 12 months ago, but had no such trouble this time around as she came through 6-1 7-6 (9/7).

The world No.2 cruised through the opening set but found life considerably tougher in the second and was forced to save two set points before eventually sealing victory in a tense tie-break.

"I knew it would never be an easy match and even when I won the first set, she was really fighting a lot in the second," said the Chinese star who now faces compatriot Jie Zheng in the next round.

Third seed Agnieszka Radwanska also advanced in straight sets, although she did not have things all her own way against Australian Open semi-finalist Eugenie Bouchard.

An evenly-contested first set was decided by a tie-break that Radwanska took convincingly and, having secured an early double-break in the second, the Pole would then go on to complete a 7-6 (7/3) 6-2 success.

No.15 seed Sabine Lisicki needed three sets to get past Karolina Pliskova, eventually beating the Czech 6-2 6-7(7/5) 6-3.

Anastasia Pavlyuchenkova also required three to see off Spain's Maria Teresa Torro 6-4 4-6 6-1, while Irina Begu of Romania beat China's Zhang Shuai 6-4 7-5.

There was one seeded casualty as Dominika Cibulkova (ninth seed) was emphatically beaten 6-4 6-0 by former US Open champion Sam Stosur.