Maria Sharapova continued to splutter through the draw and Rafael Nadal found top gear on a damp and sultry day at the Australian Open on Saturday.

Argentina's David Nalbandian, however, was on the brink of becoming the second highest men's seed to exit the tournament, but the number eight saved three match points to sink Frenchman Sebastien Grosjean 5-7, 4-6, 7-6, 6-4, 6-1 in just under four hours.

With no play possible on the outside courts due to heavy rain, top seed Sharapova was made to work hard by Italian Tathiana Garbin before reaching the last 16 with an unconvincing 6-3 6-1 victory. Second seed Nadal battered Swiss Stanislas Wawrinka 6-2, 6-2, 6-2.

Russian Sharapova, who survived a three-hour battle in searing heat in the first round, rarely played her most fluent tennis against the 30th seed but seemed unconcerned after the 69-minute match.

"I thought it was pretty good," she said. "I was a bit slow in the beginning of the match. I was letting her play her game a little to much but as the match went on I moved a lot better."

Sharapova maintained her relaxed demeanour when she told a news conference how she had taken a ride above the Costa Rican jungle on a recent holiday.

"I am very adventurous, I am pretty fearless at those things and I love to get an adrenaline rush," she said. "It's so fun, you see the trees and the waterfalls."

Sharapova will next play fellow Russian Vera Zvonereva who made a mockery of the rankings with a thumping 6-1 6-2 win over Serb Ana Ivanovic, seeded nine places above her at 13th.

Nadal was taken to four long sets by unseeded German Philipp Kohlschreiber in the last round but he overwhelmed Wawrinka, the 31st seed, in just over two hours.

MATCH POINTS

The Spanish world number two peppered Wawrinka with his full repertoire of shots from the baseline, sealing victory with a flamboyant whipped forehand down the line.

Nalbandian looked dead and buried at two sets down and 4-5, 0-40 down in the third, but he dug himself out.

"I prefer winning in three sets but it's not that simple sometimes," said Nalbandian, who also saved two match points in his opening match against Janko Tipsarevic.

"When you're three match points down anything can happen, you miss one or he plays one good point and that's it."

Russian third seed Nikolay Davydenko made short work of Fabrice Santoro, easing past the experienced Frenchman 7-6, 6-2, 6-2 in just over two hours.

Fourth seed Kim Clijsters, playing her last Australian Open, and sixth seed Martina Hingis, a three-times former champion, continued their serene progress.

Belgian Clijsters overwhelmed 29th seed Alona Bondarenko of Ukraine 6-3 6-3 in exactly an hour, and Hingis marched on with a 6-2, 6-1 demolition of Japan's Aiko Nakamura, the world number 65. Hingis and Clijsters have each dropped only nine games in the tournament.

British teenager Andy Murray faces Juan Ignacio Chela, fifth seed James Blake meets fellow American Robby Ginepri and home favourite Lleyton Hewitt takes on Fernando Gonzalez later on Saturday.