World number one Simona Halep saved three match points and overcame throbbing ankle pain to get past Lauren Davis 4-6 6-4 15-13 in a marathon third round encounter at the Australian Open on Saturday.

In a remarkable display of grit, a courageous Halep came back from the brink at 11-10 in the deciding set before finally prevailing over the determined American after three hours and 44 minutes at Rod Laver Arena.

Angelique Kerber later ended Maria Sharapova's quest for a title-winning return at the Melbourne park event, winning the battle of the only remaining former champions 6-1 6-3.

The meeting had the feel of a showpiece final but Sharapova failed to fire while German Kerber came out with all guns blazing and claimed the victory in 64 minutes.

Roger Federer marched into the second week with a 6-2 7-5 6-4 win over Richard Gasquet in just under two hours to stay on track for a 20th grand slam title. The 36-year-old defending champion has now reached the fourth round at Melbourne for the 16th time.

The Swiss was joined in the next round by Novak Djokovic, who overcame a muscle strain in his lower back but still had enough in the tank to ease past Spaniard Albert Ramos-Vinolas 6-2 6-3 6-3.

Up next for six-times Australian Open champion Djokovic is South Korean Chung Hyeon, who outlasted fourth seed and fellow young gun Alexander Zverev 5-7 7-6(3) 2-6 6-3 6-0.

Tomas Berdych overpowered Juan Martin del Potro 6-3 6-3 6-2 to reach the fourth round for the 10th time and set up a clash with Italy's Fabio Fognini, who downed French journeyman Julien Benneteau 3-6 6-2 6-1 4-6 6-3.