Sabalenka experienced late resistance in her meeting with unseeded Olga Danilovic but won 6-2 6-3 and kept alive her hopes of winning a maiden Roland Garros trophy after major successes on the hardcourts of the Australian Open and US Open.
The three-time Grand Slam champion looked in ruthless form while racing ahead 5-0 but Danilovic avoided the bagel by taking the sixth game on serve and pulled a break back to give herself a small chance to come back.
The resurgence did not last, however, as Sabalenka closed out the opening set with another break of serve and withstood another stern test in the second set to beat her 34th-ranked opponent from Serbia.
"I'm super happy with the win," Sabalenka said.
"Olga's a fighter and I knew it was going to be a fight. I enjoyed playing against her, she played like a top 10 player and I'm sure soon she will be in the top 10.
"I enjoyed our battle and I'm super happy to be through this difficult match."
Zheng, who won her biggest title at last year's Olympics, continued her good form on Parisian clay as the Chinese eighth seed moved into the second week by beating Grand Slam debutant Victoria Mboko 6-3 6-4 at a sunbathed Court Simonne Mathieu.
That match was halted briefly when the 18-year-old Mboko was down 5-3 in the second set as a fan needed medical attention but Zheng ensured her momentum was not affected when play resumed and quickly completed the victory over the Canadian.
Former semi-finalist Amanda Anisimova required treatment for a blister on her right hand before the American secured a 7-6(4) 6-4 victory over Denmark's Clara Tauson to reach the last 16 of the major where she announced herself in 2019.
Anisimova, seeded 16th, takes on Sabalenka in the next round aiming to improve her 5-2 win-loss record against the Belarusian top seed.
"We're both big hitters, so I'm sure we're going to be going at it back and forth," Anisimova said.
"Obviously she's one of the best right now. She's number one. I feel it's always a good matchup. I really enjoy the fight and the challenge she brings on.
"I'm just looking forward to it. Hopefully I can bring my 'A' game. Hopefully it'll be a good match."
--Reuters--
