Maria Sharapova continued to splutter through the draw and Martina Hingis breezed into the fourth round on a damp and sultry day at the Australian Open on Saturday.

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 in 69 minutes.

The Russian, 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.

"I thought it was pretty good," she said. "I thought 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."

Sixth seed Hingis marched on with a 6-2, 6-1 demolition of Japan's Aiko Nakamura, the world number 65, and the 26-year-old Swiss has dropped only nine games in the tournament.

The three-times former champion continued her serene progress to reach the fourth round for the ninth time in 10 visits and stay on course to win her first grand slam title since returning to the sport 12 months ago following a three-year self-imposed exile.

Second seed Rafael Nadal plays Swiss Stanislas Wawrinka, 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.

On the women's side, fourth seed Kim Clijsters meets Alona Bondarenko and number eight Patty Schnyder tackles Australian Alicia Molik.