Iga Swiatek has continued her magisterial progress at the French Open after marching into the fourth round with a 6-4 6-4 victory over her Polish countrywoman Magda Linette.
But while the former world No.1's trek to the last-16 has proved trouble-free, without the loss of a set in her three matches, it suddenly becomes serious as she'll have to be at her Sunday best when she tackles in-form Marta Kostyuk.
The Ukrainian also eased towards the showdown on another suffocatingly hot morning at sun-bathed Roland Garros on Friday, making light work of Swiss Viktorija Golubic 6-4 6-3.
But the pair are expecting their clash to have a very different feel after a week of soaring temperatures. The heatwave is set to disappear on Sunday, replaced by vastly lower temperatures, with Swiatek admitting: "We will need to adjust on the day, which is not perfect but both players have the same. We'll do our best."
Swiatek, who started her bid for a fifth Paris title by dismantling Australian teen Emerson Jones on Monday, had a slight early blip before comprehensively making amends for her surprise early loss to world No.73 Linette in Miami in March.
On the hunt for her first clay-court title since the last of her Roland Garros wins in 2024, Swiatek went a break down in the opening set but soon took control, winning three games on the bounce.
Linette, who six years ago beat an injured Ash Barty on the same Philippe Chatrier court, proved stubborn enough to break back again, but Swiatek feasted upon her weak second serve as she again restored command with three more breaks and ran out winner in an hour and 25 minutes.
But world No.15 Kostyuk is going to prove the first real barometer of the form of a player whose aura in Paris was severely dented last year when she was dethroned after three successive triumphs.
The Ukrainian has now extended her winning streak on clay to 15 matches, having won the Madrid Open - the biggest title of her career - and another tournament in Rouen, France.
Five-time French Open quarter-finalist and seventh seed Elina Svitolina continued Ukraine's fine championship in the women's singles, with a 6-2 6-3 win over Germany's Tamara Korpatsch.
Switzerland's Jil Teichmann, 170th in the world, caused the women's shock of the day, stunning Czech 10th seed and 2023 finalist Karolina Muchova 6-1 7-5 and will next face Russian eighth seed Mirra Andreeva, who beat Czech Marie Bouzkova 6-4 6-2.