Melbourne - Qualifier Denisa Allertova became the first player into the last 16 at the Australian Open after romping through against Magda Linette 6-1, 6-4 on Thursday.
The unheralded Czech took just one hour and 11 minutes to cruise past her Polish opponent to get to the fourth round of a Grand Slam for the first time.
But the big-serving world 130 admitted she found it tough as temperatures soared towards a forecast 42 Celsius on Margaret Court Arena.
Allertova ripped through the first set in just 21 minutes against the world number 74 but said she became disoriented as the extreme heat got to her for a few minutes at the start of the second set.
"I felt terrible. I didn't know what was happening at the start of the second set," she said after going 3-0 down before regathering herself to win the match.
"It was tough with the weather. I'm glad I came back. I don't know how to say how I am feeling."
Allertova's reward will be a match against either fourth
seed Elina Svitolina or 15-year-old sensation Marta Kostyuk who clash later on
Thursday.