Elina Svitolina became the sixth top 10 women's seed to exit in the Australian Open third round after she was well beaten by unseeded Garbine Muguruza on Saturday.
Two-time Grand Slam champion Muguruza won 6-1 6-2 and faces Zarina Diyas of Kazakhstan or Dutch ninth seed Kiki Bertens in the last 16 in Melbourne.
The 26-year-old Spaniard Muguruza, a former world number one but now ranked 32, failed to win two matches in a row last year after the French Open in May-June.
But the 2016 Roland Garros and 2017 Wimbledon champion spent the off-season climbing Mount Kilimanjaro to help clear her mind of tennis -- and it appears to have done the trick.
She seized the first set against fifth-seeded Ukrainian Svitolina in only 23 minutes at Rod Laver Arena.
She saved two break points while serving for the match, then sealed an emphatic victory with a powerful forehand winner.
"I was very concentrated and focused on what I wanted to do, it all went fast my way," the Spaniard said of the rapid first set.
"I played a very good match and managed to disturb her."