The Romanian recovered from a set-down and then saved three match points in the deciding set before prevailing 4-6, 6-4, 15-13 in 3 hours 45min at the Rod Laver Arena.

The final set alone lasted 142 minutes in a tie which equalled the Australian Open record for longest match in terms of games played.

This had been set in the 1996 quarter-final when American Chanda Rubin defeated Spaniard Arantxa Sanchez Vicario 6-4, 2-6, 16-14.

"I never played a third set so long. I'm almost dead," Halep said.

"My muscles are gone. 

"I don't know how my ankle is because I can't feel it any more."

Angelique Kerber also impressed today with a 6-1, 6-3 thrashing of Russia's Maria Sharapova.

The German, the Australian Open winner in 2016, completely outclassed the 2008 champion in a match lasting just 64 minutes.

Serbia's six-time winner Novak Djokovic had treatment on his lower back and leg before defeating Albert Ramos-Vinolas of Spain 6-2, 6-3, 6-3 in the men's draw.

Switzerland's five-time champion Roger Federer also progressed at the expense of Frenchman Richard Gasquet, 6-2, 7-5, 6-4, to reach the last 16.

Germany's fourth seed Alexander Zverev crashed out, however, losing in five sets to world number 59 Chung Hyeon.

Chung became the first South Korean man to reach the Australian Open fourth round ever after a 5-7, 7-6, 2-6, 6-3, 6-0 success.