WATCH | Australian Open: World No.1 Simona Halep edges Lauren Davis in marathon thriller

World number one Simona Halep saved three match points before edging an inspired Lauren Davis 4-6 6-4 15-13 in a thrilling marathon to reach the fourth round of the Australian Open on Saturday.

The Romanian fought back from the brink at 11-10 in the epic final set before serving out the match on the fourth attempt after a taxing three hours and 44 minutes on the centre court at Rod Laver Arena.

A former quarter-finalist at Melbourne Park, Halep closed out the attritional contest on the first match point, when 76th-ranked American Davis, who had gone for broke all match, fired into the tramlines, her 73rd unforced error.

The 26-year-old Halep will meet the winner of home favourite Ashleigh Barty and Japan's Naomi Osaka for a place in the quarter-finals, having carried her injured ankle through a deciding set of 142 minutes.

"I'm almost dead but it was nice that we could show good tennis," Halep said in the on-court interview, raising a laugh from the crowd. "Definitely it was a very tough match, so long, and I never played the third set so long. I just feel that my muscles are gone. My ankle is -- I don't know how it is because I don't feel it any more."

Davis, a baby-faced 24-year-old with a monster forehand, was majestic in defeat, breaking Halep three times when the Romanian served for the match and battling on after losing a toenail late in the game. She came within an inch of the biggest win of her career when she swooped forward to pounce on a speculative drop-shot and whipped a passing shot to earn three match points at 11-10.

Halep nervelessly saved them all, winning five points in a row for a galvanising hold before Davis removed her sneaker and walked gingerly to her chair. She took a medical timeout to stall Halep's momentum and the Romanian fumed on the baseline as a trainer worked on Davis's toe.

With Davis hobbled slightly, Halep moved in for the kill but the American saved five break points to frustrate her opponent, and later thanked the net cord for helping her hold again at 12-12. Halep finally breached Davis's serve at 14-13, and edged a 17-shot rally to come within two points of victory.

Apparently spent, Davis swung hard in a desperate late flurry but missed twice, a forehand sailing just wide to allow Halep to continue her bid for a long-awaited maiden grand slam title.

Here are highlights

A super Saturday of tennis begins now!

Will  @Simona_Halep progress to the second week, or will  @LaurenDavis93 upset the world number ? #AusOpen pic.twitter.com/RvAuV1txZ3

— #AusOpen (@AustralianOpen) January 20, 2018

Benefit of the doubt: it's not luck when you're number one... #AusOpen pic.twitter.com/I85T1nyMTY

— #AusOpen (@AustralianOpen) January 20, 2018

Yeh, nah - you can't stop those. #AusOpen pic.twitter.com/OOU6vYi1vw

— #AusOpen (@AustralianOpen) January 20, 2018

Lauren #Davis is putting it all on the line against Simona #Halep.

But the world number  holds in a vital game: she leads 4-2 in the second set. #AusOpen pic.twitter.com/vfzOuxCjIO

— #AusOpen (@AustralianOpen) January 20, 2018

Lauren #Davis = #AusOpen pic.twitter.com/clfVAsfLMg

— #AusOpen (@AustralianOpen) January 20, 2018

Defence #AusOpen pic.twitter.com/8LSk8bnm4n

— #AusOpen (@AustralianOpen) January 20, 2018

Heads up! #AusOpen pic.twitter.com/douS5xinxY

— #AusOpen (@AustralianOpen) January 20, 2018

Not. Going. Anywhere! 

A huge break and this incredible match takes another turn... and Davis is pumped! #AusOpen pic.twitter.com/iC9eLQI0Ww

— #AusOpen (@AustralianOpen) January 20, 2018

How?!

What a match this is on @RodLaverArena! #AusOpen pic.twitter.com/ZgU6gsLaWc

— #AusOpen (@AustralianOpen) January 20, 2018

Current feels. #AusOpen pic.twitter.com/wafJLbEmlR

— #AusOpen (@AustralianOpen) January 20, 2018

No words.

Just enjoy this. #AusOpen pic.twitter.com/OFhA1m49lt

— #AusOpen (@AustralianOpen) January 20, 2018

Can this match never end?#AusOpen pic.twitter.com/E7HHfnbam1

— #AusOpen (@AustralianOpen) January 20, 2018

And we go on...

Twitter - who's your pick? #AusOpen pic.twitter.com/2a5S4yPzPh

— #AusOpen (@AustralianOpen) January 20, 2018

Is there anything this match doesn't have?!

A medical timeout for Lauren Davis locked at 11-11 against Simona Halep.
This is intense. #AusOpen pic.twitter.com/5wztMP3caD

— #AusOpen (@AustralianOpen) January 20, 2018

What about this woman's backhand?!#AusOpen pic.twitter.com/IO9Q5RujeZ

— #AusOpen (@AustralianOpen) January 20, 2018

Clutch.

The world number  showing her quality! #AusOpen pic.twitter.com/dViSsYlnjn

— #AusOpen (@AustralianOpen) January 20, 2018

#AusOpen pic.twitter.com/pyeFygJqiY

— #AusOpen (@AustralianOpen) January 20, 2018

There aren't enough words invented to describe this match.

This'll do. #AusOpen pic.twitter.com/qI6rageBar

— #AusOpen (@AustralianOpen) January 20, 2018

RT if you think this is match of the tournament so far...#AusOpen pic.twitter.com/qyiRHGsYTM

— #AusOpen (@AustralianOpen) January 20, 2018

Think you can win this @Simona_Halep ? #KiaTennis #AusOpen @Kia_Motors pic.twitter.com/ItIvBO944p

— #AusOpen (@AustralianOpen) January 20, 2018

Calling in reinforcements!

New balls brought to @RodLaverArena as the clock ticks over three hours and 30 minutes... #AusOpen pic.twitter.com/cAgJqenUCr

— #AusOpen (@AustralianOpen) January 20, 2018

An epic.

There's no other way to describe it. #AusOpen pic.twitter.com/yh3yHzhbUV

— #AusOpen (@AustralianOpen) January 20, 2018

“My muscles are gone. My ankle - I don’t know how it is because I can’t feel it... It's great to be in 4R."

The world number , @Simona_Halep wins an incredible match to keep her #AusOpen campaign alive. pic.twitter.com/ddtJTR3ewL

— #AusOpen (@AustralianOpen) January 20, 2018

(Inputs from Reuters)