Tenacious Australian Daria Gavrilova beat Kristina Mladenovic in a white-knuckle thriller in which the third set went to 11-9 on Friday night.
Gavrilova shed tears when she finally clinched victory 6-4, 4-6, 11-9 on Hisense Arena. "I've got nothing in my head and I'm just really excited," she said. "I really want to hug the whole stadium."
Gavrilova, 21, recently celebrated becoming an Australian citizen and has accelerated through the rankings over the past year. 
Moving from outside the top 100 to her current position at No.39, she has won fans with her unrelenting, high-energy brand of tennis. A year older and nearly 20 centimetres taller, Frenchwoman Mladenovic also broke through in 2015, moving from No.81 to finish the year at No.29.
Gavrilova's first-set win always looked likely, although Mladenovic managed to take four games. Where Mladenovic appeared agitated, the Australian wore a slight smile as she bounced between points, clearly enjoying the cheers of a rowdy and patriotic crowd.
Early in the second set, Mladenovic tried to pop the ball over the net for a sneaky winner, only to not quite make the height and have it bounce back at her feet.
She spent a moment head down, her frustration clear for all to see.
But when Mladenovic regained her composure and fought back, it was Gavrilova's turn to be annoyed. She yelled and hit the ball high into the air.
When she found herself early in third set and out of challenges, she exchanged words and a furious look with the chair umpire.
The match then became an arm-wrestle - each time Mladenovic edged ahead, Gavrilova fought back.
The were times when the taller woman appeared too good at serving, too strong at the net, but Gavrilova played every shot, persistent and fiercely competitive until the end.
The crowd chanted for "Dasha" - they sang, they cheered. When she was losing and fell to her knees they roared and she got up, with another smile.
Gavrilova did not know then who she would play next, but clearly could not wait.
"I just want to play again, I want to play again on Sunday," she said.
"Spare a thought for Daria Kasatkina, the teenager annihilated by Serena Williams on centre court in a third round match.
The contrast between the players could could hardly be more stark.
Even at the age of 34, and facing ongoing knee problems, Williams still looks unbeatable. In an exhibition of power-hitting and unplayable serves, the world No.1 looked as competitive and passionate as ever.
Kasatkina is just 18 years old and is ranked No.69 in the world.
She made the third round in last year's US Open, and despite the 6-1, 6-1 loss to Williams equalled her best grand slam outing.
While Williams looked typically calm and focused as she walked onto Rod Laver Arena, Kasatkina seemed to be overawed by the occasion.
The Russian served up multiple double-faults in the first game, mistakes one can hardly afford to make when facing the best woman player in the world.
The crowd cheered when she managed to win her first game, but Williams hit back with a near-perfect service game in which Kasatkina didn't manage a single point.
This was the first time Kasatkina and Williams played, but it may not be their last.
After the match, Williams could be heard praising her opponent as they shook hands at the net.
"I love your game, great forehand," she said.
Next time the younger woman will be a little older, with more match experience, and may prove a greater challenge to the queen of world tennis.