MELBOURNE (AFP) ― The women’s top seeds cruised through in straight sets Friday with Agnieszka Radwanska, Angelique Kerber and Li Na leading the drive into the Australian Open fourth round.

Seeded four, five and six respectively, they were joined by Ana Ivanovic who won a battle of former world numbers ones by beating Jelena Jankovic.

World number two and second seed Maria Sharapova plays a blockbuster evening match on Rod Laver Arena against seven-time Grand Slam champion Venus Williams later on Friday.

Poland’s Radwanska is the form player this year, winning her 12th match in a row without dropping a set in her best ever start to a season, something she put down to a new-found confidence.

The world number four proved too strong for Britain’s Heather Watson in a 6-3, 6-1 thumping as she searches for her first Grand Slam title.

“I think I’ve never won 12 matches in a row,” the Pole said. “I’ve never played two tournaments before Australian Open. It was my first time I played Auckland and Sydney and it was a good start. I can’t complain.”

She said she changed nothing in her game during the off-season, but is feeling more confident about herself.

“I’m very confident from the beginning and just happy that I can play really my best tennis from the beginning of the year,” said the 23-year-old.

Radwanska, who won lead-up tournaments in Auckland and Sydney, next faces 13th seed Ivanovic who eased past Jankovic 7-5, 6-3.

Ivanovic won the French Open title in 2008, but has failed to make any significant impact at a Grand Slam since. But she proved too hot to handle for Jankovic, who has also struggled to recapture her best form in recent years.

China’s top player Li is also a former winner at Roland Garros, in 2011, and she breezed past Romania’s Sorana Cirstea 6-4, 6-1.

The sixth seed, a finalist at Melbourne Park in 2011, next plays 18th-seeded German Julia Goerges, who beat Li’s compatriot Zheng Jie 6-3, 1-6, 7-5 in their third round clash.

But it wasn’t all plain sailing for Li in a seesawing first set, with the Chinese number one making a slew of unforced errors and double faults in throwing away two service games.

Kerber, who was celebrating her 25th birthday, was given a second set workout by young American Madison Keys but was never seriously threatened in a 6-2, 7-5 win under the roof of the Rod Laver Arena, which was closed due to rain.

Kerber has never been beyond the third round at Melbourne Park before and next meets 19th-seeded Russian Ekaterina Makarova, who beat 11th-seeded Frenchwoman Marion Bartoli 6-7 (4/7), 6-3, 6-4.

“It was a very tough match because Madison is a great young player,” said Kerber, after being presented with a chocolate birthday cake on court.

“I really have nothing to lose,” added the German, who won tournaments in Paris and Copenhagen last season and was the first women from her country to finish in the year-end top five since Steffi Graf in 1996.