The women's fourth round matches so far completed on Monday have seen Dominika Cibulkova upset Maria Sharapova 3-6, 6-4, 6-1, Victoria Azarenka beat Sloane Stephens 6-3, 6-2, Simona Halep down Jelena Jankovic 6-4, 2-6, 6-0 and Agnieszka Radwanska thrash Garbine Muguruza to all move into the quarter finals.
The first women's Round of 16 match-up on Monday on Rod Laver Arena with former world No. 1 and Australian Open champion Sharapova taking on 20th-seed Slovak Cibulkova.
The Russian 26-year-old started the match well also winning the first set six games to three with her serve on song and with her managing to break Cibulkova's serve on three occasions.
However, Cibulkova has played perhaps the best tennis of her career to reach the fourth round in Melbourne and she wasn’t about to throw it in after losing the first set.
The 24-year-old Slovak took advantage of 15 unforced errors in the second set from Sharapova to take her game up a notch as well to take it out six games to four.
That set up a deciding third set with a quarter-final clash on the line, but it was Cibulkova who dominated breaking Sharapova's serve three times and dropping just the one game.
The Russian hit 19 unforced errors in the third set alone and seven double-faults to be bundled out of the Australian Open in the fourth round.
Cibulkova is now into the Australian Open quarter finals for the first time where she will face Romanian Halep.
Another former world No.1 and defending Australian Open champion Azarenka then had an easier time of things up next on Rod Laver Arena with the Belarusian cruising into the quarter finals with a straight-sets win over 20-year-old American 13th-seed Stephens.
It was a commanding performance from Azarenka who now not only is the highest-ranked player left in the women's draw, but now a firm favourite to make it back-to-back Australian Open titles with Sharapova and Serena Williams both out of the tournament.
It was a solid showing from Azarenka against Stephens with the Belarusian 24-year-old winning 73 per cent of her first serves, 13-of-17 net points and breaking the American's serve three times while not dropping her own once.
Azarenka will now face world No. 5 from Poland Radwanska in the quarter finals.
The third women's fourth round match of the day took place on Hisense Arena with yet another former world No. 1 in action as currently eighth-seed Serb Jankovic did battle with emerging 11th-seeded Romanian Halep.
Jankovic was looking to make it to the quarter finals at the Australian Open for the first time since 2008 but she had a horror start in the first set hitting 21 unforced errors as her 22-year-old opponent took advantage to win it six games to four.
The 28-year-old Jankovic responded well in the second set, though, limiting her unforced errors to just 10 as she managed to break Halep's serve three times to claim the set six games to two.
That set up a third set with a quarter-final berth on the line and it was Halep who completely dominated not dropping a single game as she advanced to the quarter finals at any Grand Slam for the very first time.
In the final match of the night on Monday, Radwanska booked her place in the last eight for the fourth consecutive year at Melbourne Park with a clinical 6-1, 6-3 victory over unseeded Spaniard Garbine Muguruza.
Radwanska, 24, gave a tennis lesson to her 20-year-old opponent, who had previously never advanced further than the second round of a grand slam.
Muguruza, who eliminated 10th seed Caroline Wozniacki, did herself no favours, unable to convert any of her six break-point opportunities.
It brought to an end an impressive summer that started with her first WTA Tour title with victory in the Hobart International.
Radwanska has made the final eight four successive times but has never gone further.