World No.1 Serena Williams’ Madrid Open title defence was off to a battling start on Sunday, beating Kazakh qualifier Yulia Putintseva 7-6 (7-5) 6-1 but China’s Li Na fell at the first hurdle.

Putintseva had come through two rounds of qualifying and seemed to handle the warm conditions better early in a tight first set.

Both women broke each other once and Putintseva managed to save another three break points to force the set into a tie-break.

However, the world No.88 finally crumbled at 5-4 in the tiebreak as she fired long and Williams served out the set before taking control in the second, breaking four times to close out the match.

“I felt a little sluggish at the beginning but, happily, I was able to win,” said the 15-time grand slam winner.

“I know I will need to play better as each match goes on.”

Williams believes the warm conditions in the Spanish capital should be to her advantage as the tournament progresses.

China’s world number five Li Na, the 2011 French Open champion, was the biggest name to fall when she was taken apart by American Madison Keys 6-3 6-2.

Keys had only entered the tournament as a lucky loser thanks to the withdrawal of Tamira Paszek after being beaten by compatriot Bethanie Mattek-Sands in the qualifiers.

But she dominated with her heavy groundstrokes producing a series of errors from the Chinese.

World No.10 Caroline Wozniacki was the other major name to be eliminated as the former world No.1 was beaten by Yaroslava Shvedova of Kazakhstan 6-2 6-4.

Venus Williams was forced to pull out of the tournament with a back injury.

Eighth seed Petra Kvitova was forced to go the distance against Yanina Wickmayer.

The world No.36 took the first set 6-4, but Wimbledon winner Kvitova bounced back to win the next two 7-5 6-4.

Sixth seed Angelique Kerber also took three sets to beat Su-Wei Hsieh 3-6 6-3 6-2 and 16th seed Ana Ivanovic came from a set down too as she overcame Mattek-Sands 6-7 (10-12) 6-3 6-2.

Agnieszka Radwanska, the fourth seed, had a comfortable afternoon as she saw off Tsvetana Pironkova 6-2 6-4 to set up a meeting with Britain’s Laura Robson and Marion Bartoli is also safely through after her opponent Elena Vesnina retired with the score 6-3 3-0 in the Frenchwoman’s favour.

American Varvara Lepchenko outlasted 12th-seeded Robeta Vinci 6-1 1-6 6-2.

Other seeded winners included Marion Bartoli, Dominika Cibulkova, Nadia Petrova and Maria Kirilenko.