Top seed Iga Swiatek moved into the last-16 at the French Open on Saturday following a straight sets win over Danka Kovinic from Montenegro.
The world number one's 31st consecutive victory came at a cost of eight games - double the tally from her first two matches combined at the competition.
The 6-3, 7-5 triumph came after 90 minutes of play in which Kovinic absorbed Swiatek's power and injected finesse .
"I had to adjust a little bit more to what she was doing and play a little bit more smart," said Swiatek.
"I changed the tactics in second set a little bit to play less risky but then I did some mistakes and I lost my breaks. I'm not perfectly happy with that but overall I'm happy with the performance."
The 2020 champion will take on the Chinese teenager Qinwen Zheng after she benefited from Alizé Cornet's retirement due to injury.
The 19-year-old, who eliminated the 2018 champion Simona Halep in the second round, was leading the French veteran 6-0, 3-0 when Cornet called it a day.
Her withdrawal brought boos from parts of the centre court crowd. "That hurt more than my injury itself," said Cornet.
"You know, you can't generalise things. It was just a handful of people in the stadium so maybe they made a lot of noise.
"But it's really too much when you see everything I've been giving on the court for so many years."
The partisans also lost Léolia Jeanjean. Irina-Camelia Begu dispatched her 6-1, 6-4 to reach the last-16 for the first time since 2016.
Jeanjean, 26, who began the tournament ranked 227 in the world, is likely to rise 70 places following her performances in her first Grand Slam tournament.
"It's been pure joy to experience this tournament," she said. "It's always a little bit difficult to manage a defeat. It doesn't make me happy, of course, but with a bit of hindsight, I had a tremendous time. It was an amazing point in my life, and I'm very happy."
Twentieth seed Daria Kasatkina also progressed to the last 16. She saw off the unseeded American Shelby Rogers 6-3, 6-2 in 79 minutes.
