Kazakhstan's Elena Rybakina, seeded 22nd, will face Latvia's Jelena Ostapenko in the quarter-finals.
World number one Iga Swiatek has crashed out of the Australian Open with a 6-4, 6-4 defeat by Wimbledon champion Elena Rybakina on Rod Laver Arena.
Kazakhstan's Rybakina advanced to the quarter-finals of the season's opening Grand Slam for the first time with an impressive display against the misfiring Pole.
"It was a really tough match and I really respect Iga because of the strike she has and the Grand Slams," said Rybakina after Sunday's match.
"She's a young player and she plays really well. Today I think was serving also good, just struggling on one side. Then in the important moments I played really well and it made a difference."
Rybakina, seeded 22nd, will face Latvia's Jelena Ostapenko in the quarter-finals.
A rough start
Swiatek, the reigning French Open and US Open champion, got off to a rough start, surrendering her opening service game after receiving a warning from the chair umpire over the time she took for her pre-match preparations.
She fought back to level the scores by the fourth game but Rybakina would break again, clinically punishing the Pole's second serve to take the opening set.
Swiatek looked to have recovered after she rattled off three straight games at the start of the second set behind a more aggressive forehand, only for Rybakina to haul herself level with another break of serve.
The Russia-born right-hander broke Swiatek again at 4-4 in the second set before holding her own serve in a convincing fashion to close out the match.
Rybakina's win sees her progress to a third Grand Slam quarter-final having also reached the last eight at the 2021 French Open before winning Wimbledon last year.