Women's top seed Iga Swiatek and seventh seed Coco Gauff both suffered fourth-round eliminations from the Australian Open on Sunday.
World number one Swiatek, who had not dropped a set en route to the last 16, went down 6-4 6-4 to reigning Wimbledon champion Elena Rybakina in one hour and 29 minutes.
Despite storming into a 3-0 lead in the second set, Swiatek could not keep up the intensity and lost six of the next seven games to bow out of the opening Grand Slam of the year.
Rybakina - who hit six aces on the day - advances to meet Jelena Ostapenko in the quarter-finals after the Latvian 17th seed came up with a shock win of her own over Gauff.
Ostapenko took one hour and 33 minutes to record a 7-5 6-3 success over the 18-year-old, whose serving success rate dropped dramatically in the second set.
Gauff earned the first break of the match in the third game, but Ostapenko broke back straight away and then impressively beat away six more break points for the American.
Hitting 30 winners, the 2017 French Open champion secured her spot in the last eight alongside Rybakina and third seed Jessica Pegula, who saw off Barbora Krejcikova in straight sets.
Jiri Lehecka - who stunned Cameron Norrie in round three - continued his barnstorming run with a four-set win over Felix Auger-Aliassime, while Karen Khachanov and Sebastian Korda beat Yoshihito Nishioka and Hubert Hurkacz respectively.
Jannik Sinner faces Stefanos Tsitsipas in an eye-catching battle at the Rod Laver Arena later on Sunday, while Victoria Azarenka pits her wits against Lin Zhu.
Ben Knapton
