Maria Sharapova was handed an Australian Open hiding by Angelique Kerber in the third-round battle of the former champions, while Simona Halep saved three match points in an extraordinary encounter against Lauren Davis.
It was the most anticipated match of the tournament so far but Kerber carried on the tremendous form she has shown to start the season and romped to a 6-1 6-3 victory in just 64 minutes.
The German endured a nightmare 2017 after winning the Australian Open and US Open titles in 2016 and climbing to world number one but is unbeaten so far this year after winning the warm-up event in Sydney.
Given the wobbles endured by the top seeds this week and the wide open nature of the draw, Kerber is fast establishing herself as the title favourite.
The 30-year-old said: "I have so many great memories from this court. I came out and I was trying to enjoy every point. Maria's a champion, she played so good the last few weeks. I was really trying to play my game. I was really happy we have 2018 and not 2017.
"I learned a lot from the last 24 months. I had a great 2016 and last year was tougher but everyone who knows me knows I never give up."
Sharapova wanted to see how her level compared to the top players and in the first set the answer was not very well at all. Kerber was quicker, sharper and far more consistent, allowing her opponent just three of 14 points on her first serve.
When Kerber moved 2-0 ahead in the second set, it seemed the match that had been billed as a potential classic would turn into an embarrassing rout.
But, if all else fails her, Sharapova will always have her competitive instinct and she dug in to retrieve the break and give herself a foothold in the match.
It did not last long, though. The Russian simply could not find the consistency to match Kerber's excellence and the 21st seed did not falter, raising her arms in the air with glee after Sharapova pulled a backhand well wide, her 26th unforced error.
Simona Halep saved three match points and served for victory four times in an extraordinary encounter against Lauren Davis before eventually booking her spot in the fourth round of the Australian Open.
The top seeds in the women's tournament have all had their dramas this week but none quite like this.
American Davis traded toe to toe with the world number one for three hours and 44 minutes but Halep finally forced a match point and took it for a 4-6 6-4 15-13 victory.
The 26-year-old said: "Definitely it was a very tough match. So long. I never played the third set so long. I was very happy I could stay and win it. I'm almost dead but I'm happy we could show great tennis."
The final set lasted two hours and 22 minutes while the 48 games equals the most for a women's match in Australian Open history, tying the 1996 quarter-final between Chanda Rubin Arantxa Sanchez Vicario, which Rubin won 6-4 2-6 16-14.
Halep suffered an ankle injury in round one but looked to have shrugged it off in a convincing win over Eugenie Bouchard on Thursday.
Her biggest problem here was Davis, ranked 76 but playing significantly above that, as she came from a break down to take the opening set in her first ever match against a world number one.
Halep hit back to level and it appeared the danger might have passed but Davis simply would not go away.
Three times the top seed served for a place in the fourth round at 5-4, 6-5 and 8-7 and three times Davis broke back.
