MELBOURNE, Jan 20 - 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 eighth 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 play suspended 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 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."

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

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.

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, third seed Nikolay Davydenko meets Fabrice Santoro and home favourite Lleyton Hewitt takes on Fernando Gonzalez later on Saturday.