World number 10 Caroline Garcia of France moved into the quarterfinals of the Pan Pacific Open in Tokyo on Thursday.
The 29-year-old beat Ukraine's Anhelina Kalinina, ranked 28, 6-4, 6-3.
"The condition is quite extreme here. Very hot and humid," Garcia said after the match as the temperature hit 33 Celsius (91.4 Fahrenheit).
"So I'm very, very pleased" with the win, she said.
In the next round, "I want to try to play my game, to be aggressive... to do the most wins I can," she added.
Garcia was beaten last week by Greece's Maria Sakkari at the Guadalajara Open.
World No 6 Sakkari, who ended her four-year wait for a second WTA title in Guadalajara, faces Japan's Misaki Doi in the evening on Thursday.
The 28-year-old had come up empty in six finals since her breakthrough victory in Rabat in 2019.
That included the Guadalajara final last year, when she lost to American Jessica Pegula, and a loss to Coco Gauff in the final of the Washington Open this year.
On Friday, four-time Grand Slam champion Iga Swiatek will face Veronika Kudermetova, while world No 4 Pegula will play Daria Kasatkina.
Australian Open finalist Elena Rybakina has withdrawn, citing health reasons.
The tournament concludes on Sunday.