Kontaveit, 24, from Tallinn, had seen last season curtailed due to illness, but the break appears to have had a positive impact. After beating local player Astra Sharma in straight sets in Melbourne in round one, and Sandra Sorribes Tormo of Spain in three sets in round two, the Estonian pulled off a stunning victory against Swiss world number eight Belinda Bencic late last week, setting her up with the round four matchup with Swiatek.

While the previous and only time the pair had played each other, in Cincinnati last year, Kontaveit won in two sets, this time, the Pole, 18, made her work for the victory in a game which lasted two hours and 42 minutes – around a whole two hours longer than the duration of the Bencic match – and finishing around 6.30 a.m. Estonian time, Monday afternoon in Australia.

In the first set, Kontaveit lost her serve in the opening game and soon was 2:0 behind, only to pull back to 3:2, then 4:3, before losing her serve, and again three games later, leaving the score 5:5. However, Swiatek held on to take the set to a tie-break, which she managed 7:6 (4).

Between the first and second sets, the Pole took a medical break, emerging with a taped leg. The second set started off again with Kontaveit losing her opening serve, again pulling back level to 2:2 and, after Swiatek had been ahead 4:3, the Estonian was able to win four more games to her opponent's one, to make it 7:5, and even on sets.

"I'm still shaking...I couldn't be happier!"

Bravo, Anett Kontaveit.

The 28th seed will face fourth seed Simona Halep in the quarterfinals. #AO2020 | #AusOpen pic.twitter.com/WEF6VhG3fD

— #AusOpen (@AustralianOpen) January 27, 2020

The decisive third set went much more Kontaveit's way, winning the first three games and nearly the fourth, without answer, but Swiatek was able to hold her serve, making it 3:1. Two more games to Kontaveit brought it to 5:1 and seemingly the Estonian had things in the bag. However, Swiatek found her pace again and won the next four games, making it 5:5 again. Finally, Kontaveit both held her serve, and broke her opponent's, to take the set 7:5 and thus the match.

"It was a real battle, but I'm so glad I won and made it to the quarterfinals for the first time," Kontaveit, who is the first Estonian to get to the Australian Open last eight, said after the game.

"I'm still shaking I couldn't be happier right now," she added.

"I tried to fight for every point and I am very pleased that I was finally able to win."

Both players served up four aces in the match, Kontaveit made three double faults to twice that number by Swiatek. Kontaveit had a 61 percent first serve success rate, compared with her opponent's 49 percent, according to ERR's sports portal.

The timing of Kontaveit's quarter final match with Simona Halep is to be confirmed. The pair have met twice before, the Romanian winning both times, most recently in 2017.