One of the most dramatic grand slam days in recent memory saw Serena Williams knocked out, Caroline Wozniacki sent into retirement and Coco Gauff write more headlines by beating defending champion Naomi Osaka.
It was another remarkable achievement for the 15-year-old, while Williams' wait for a record-equalling 24th grand slam singles title goes on after defeat by China's Wang Qiang.
The fitting final act saw Roger Federer conjure a Houdini act to beat John Millman in five sets. Stefanos Tsitsipas was another big name to go out, beaten by Milos Raonic, but there were comfortable wins for Novak Djokovic and Ashleigh Barty.
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Good guy Rafa
Rafael Nadal's compassionate treatment of a ball girl who he accidentally hit hard in the head with a miscued forehand on Thursday made headlines around the world.
The world number one said it was one of his scariest moments on a tennis court but thankfully young Anita was unhurt and Nadal went to check on her again on Friday.
Furry and not-so-furry friends
A compulsory extra-curricular activity for tennis players Down Under is meeting the native wildlife. The animals came to the players at Melbourne Park on Friday, with Dominic Thiem making friends with a koala and John Isner hanging out with something considerably less cuddly.
Women: Naomi Osaka (3), Serena Williams, (8), Madison Keys (10), Ekaterina Alexandrova (25), Elena Rybakina (29)
Men: Stefanos Tsitsipas (6), Roberto Bautista Agut (9), Guido Pella (22), Dusan Lajovic (24)
Who's up next?
Rafael Nadal returns to Rod Laver Arena to take on fellow Spaniard Pablo Carreno Busta in the third round on Saturday.
Should he win and Nick Kyrgios defeat Karen Khachanov, they would set up a blockbuster fourth-round meeting.
Karolina Pliskova kicks off proceedings against Anastasia Pavlyuchenkova while Simona Halep faces Yulia Putintseva and Elina Svitolina takes on Garbine Muguruza.