Reigning champion Iga Swiatek celebrated her 23rd birthday by brushing aside Marie Bouzkova to reach the French Open last 16 on Friday.
Swiatek had to save a match point to avoid an upset defeat by fellow four-time Grand Slam champion Naomi Osaka in a second-round thriller, but she was never in trouble during a 6-4, 6-2 win over Czech Bouzkova.
The world number one is a red-hot favourite to lift the Coupe Suzanne Lenglen for a third straight year and become only the fourth woman to win four Roland Garros titles in the Open era.
She was much closer to her best form on Friday, hitting 34 winners and making only 19 unforced errors. The Polish star's win-loss record at the tournament stands at 32-2 and she has never failed to reach the second week.
Iga Swiatek plays a shot against Japan's Naomi Osaka during their second round match of the French Open. AP
"I feel good physically, I had a day off yesterday," said Swiatek. "I don't feel like the match (against Osaka) stayed with me but we'll see at the end of the tournament."
Swiatek will play Russia's Anastasia Potapova in the next round on Sunday. The Polish star's win-loss record at the tournament stands at 32-2 and she has never failed to reach the second week.
Gauff held off a late fightback from Australian Open semi-finalist Dayana Yastremska to win 6-2, 6-4 in the first match of the day on Court Philippe Chatrier.
The reigning US Open champion has an excellent record at Roland Garros, having previously reached two quarter-finals and the 2022 final which she lost to Swiatek.
The 20-year-old failed to serve out the match when leading 5-2 in the second set, but saved three break points in the 10th game before getting over the line.
"When it was time to close out and the games were getting close and tight, I was trying to just remind myself I'm in the better position," Gauff said. "I'm the one up a set and double break, so I was just reminding myself of that."
Gauff will play Elisabetta Cocciaretto for a last-eight berth, after the unseeded Italian beat Russian 17th seed Liudmila Samsonova in straight sets.
Angry Rublev crashes out
Rublev became the biggest casualty in the men's draw so far, as he fell to a surprise straight-sets defeat by Italian Matteo Arnaldi.
Rublev, who lifted the Madrid Open title last month, repeatedly smashed his racquet in frustration as he made 37 unforced errors in an erratic display.
"Completely disappointed with myself the way I behaved, the way I performed," admitted the Russian. "The problem is the head, that today basically I killed myself, and that's it."
Arnaldi will face either former runner-up Stefanos Tsitsipas or China's Zhang Zhizhen in the last 16.
Sinner barely had to break sweat, though, saving the only break point he faced in a dominant display against Kotov.
The Australian Open champion, who will overtake Novak Djokovic as world number one if he reaches the final, will next take on either home hope Corentin Moutet or Austrian Sebastian Ofner for a place in the quarter-finals. Sinner, who has only lost two matches so far this year, is yet to drop a set in the tournament.
Agence France-Presse