Anastasia Pavlyuchenkova defeated the in-form Svetlana Kuznetsova 6-3 6-3 to be the first player who moves into the quarterfinals.
Nastya played one of her best tennis to start strongly the match and take a 5-1 lead. Coming after one of the longest matches here at Australian Open, Sveta looked tight and wasn't able to do something against the fresh Pavlyuchenkova.
In the second, somehow Kuznetsova leveled at 3-3, but from there, the younger Russian got right back on track and closed the contest in one hour and 8 minutes.
"I'll take it. I mean, it's super exciting. I'm so happy. I was always wondering why I could never have a good start here in Australia after good preseason, good offseason, and a lot of practicing. But now it seems like I found a way, and I'm super excited to still be in the second week here."
Quarter-final: Anastasia Pavlyuchenkova (24) vs Venus Williams (13)
Venus Williams kept her amazing form to overcome one of the qualifiers, Mona Barthel 6-3 7-5.
The German was one of the surprises of the tournament, coming after a tough 2016 year full of injuries. She managed to get to this stage by performing really impressive, but against Venus it looked to be too tough.
The American didn't let her opponent to breath, playing aggressively and safe to grab the first set. Barthel found a way to create more damage until 5-5 in the second, but the former world nº1 swept the next two games and secured the win.
"But really, at the end of the day, it's about walking to the net, shaking hands as the winner. However that happens, two sets or three sets, that's how I want to walk to the end, as a winner."
Garbiñe Muguruza closed out the unexpected route of Sorana Cirstea to book the ticket for her first quarter-finals appearance at Melbourne Park.
Cirstea was enjoying her best results here in Australia, after sending home the 10th seed in the second round. From the other side, Muguruza was working to get her form match by match and against the Romanian, she showed one of her most consistent game.
The big hitter scattered winners to take early breaks in each set and by consolidating the advantage she had no problem to put an end to the match after only one hour and 5 minutes.
"I am very happy. I went through the match very concentrated, looking to play positively. Was an important match for me. A couple of times in the last three years, I've lost in this round. Was the first time I go through. I'm in the quarterfinals. So I'm very excited about that, and I'm still excited!"
Quarter-final: Coco Vandeweghe vs Garbiñe Muguruza (7)
Coco Vandeweghe produced the biggest shock of the tournament so far, by knocking out the defending champion Angelique Kerber 6-2 6-3 and advanced to her 2nd Grand Slam quarterfinals.
Kerber definitely wasn´t at her best, but Coco took this as an extra motivation to play probably the match of her life. The American started on fire and never looked back, pushing the world nº1 to defend her powerful shots all the time. There was a try of coming back when Angie started the second set by breaking the serve and taking a 2-0 lead, but it proved to be a false alarm.
Converting 4 of 6 break points and with a total of 30 winners to only 20 unforced errors, Vandeweghe stunned Kerber on the Rod Laver Arena to get her well-deserved spot in the last eight after only 68 minutes.
"I believe this is my first No.1 win, so I'll take that. I was feeling bad out there but you've just got to keep at it and keep going. I had to trust my game to beat her and I did."