Naomi Osaka shrugged off the heat and another first-set freeze to breeze past Elise Mertens 6-3, 6-3 in the second round of the Bad Homburg grass-court tournament on Tuesday.
For the second match in a row, Osaka raced to a 5-0 lead in the first set before allowing her opponent to fight back.
On Sunday, in the first round, Magdalena Frech cut the gap to 5-4 before Osaka reasserted control.
Belgian Mertens came back to 5-3, before Osaka sealed the set before cruising through the second to reach her first quarterfinal of 2026.
Quarterfinals unlocked 🔓@naomiosaka races past Mertens for a spot in the quarterfinals for the first time here in Bad Homburg!#BHO26 pic.twitter.com/mwHrbb8SMc
— wta (@WTA) June 23, 2026
"In my last match I had a huge dip in the first set, and this time I tried to be pretty stable," Osaka said. "So it's honestly really fun to learn match by match."
Osaka, the Japanese fifth seeded, said she was not bothered by temperatures in the mid-30s.
"I'm pretty heat-tolerant," Osaka said. "I really love the heat. I kind of prefer it. It was hot in Paris a few weeks ago and I also enjoyed that, so I kind of want it to be hot."
In the next round, she will face the winner of the match between Mirra Andreeva and Ekaterina Alexandrova, who meet on Wednesday.
Andreeva will be playing her first match since winning Roland Garros.
Two days after winning the Berlin title to climb to 10th in the world, Czech Linda Noskova fell to Romanian Elena-Gabriela Ruse 6-1, 6-3.
Novoska's first-round match was delayed because she also reached the delayed doubles final in Berlin which she won, with Alexandrova on Monday.
In the second round, Ruse will face Anna Kalinskaya. It will be the first meeting between the two players.
Ukrainian Elina Svitolina battled past Russian Liudmila Samsonova 3-6, 6-3, 6-2 in two hours 12 minutes and will face Chinese world No 52 Wang Xinyu.