The world number two Italian Sinner will face 57th-ranked Fabian Marozsan of Hungary in the Beijing quarter-finals.
“It was a very tough match today,” four-time Grand Slam champion Sinner said. “I felt like he was serving great.”
Sinner said that he lost a bit of concentration during the second set but quickly recovered to steamroll past the 68th-ranked Atmane in the deciding set.
“I started off very well in the third set then I saw (Atmane) struggling a bit physically.
“It’s not how you want to win a match but very happy to be again in the next round.”
Atmane declared it would be a fight with two aces in the first game and made Sinner work for the first set.
Atmane sent down six more aces in the second and broke the 24-year-old Sinner to force a deciding set.
With the Frenchman flagging, Sinner raced to victory.
In the women’s draw, qualifier Aliaksandra Sasnovich of Belarus stunned 14th-ranked Naomi Osaka of Japan, the four-time major champion.
The 31-year-old world no. 130 fought back to win 1-6, 6-4, 6-2.
Elsewhere it was more routine as Swiatek breezed past home player Yuan Yue, cruising into round three with a 6-0, 6-3 victory.
The world number two from Poland next faces Colombia’s Camila Osorio, ranked 83rd.
Swiatek broke early to set the tone for an ultimately one-sided match against Yuan, winning the first set without dropping a game when the wildcard from China fired long.
Cheered on by her home crowd, the world no. 110 made a better fist of it in the second set but Swiatek wrapped things up when Yuan returned into the net.
Swiatek, who came to the Chinese capital after winning the title in Seoul, gave kudos to her opponent afterwards.
“She was reading the court pretty well,” Swiatek said.
“It wasn’t easy and every game was tight.”
The six-time major champion is the top seed in Beijing after world number one Aryna Sabalenka withdrew with injury.
Swiatek won the prestigious WTA 1000 tournament in 2023 but missed the competition last year citing personal matters.
It later transpired she had accepted a one-month doping ban after testing positive for a prohibited substance.
“I have great memories,” Swiatek said of her history in the Chinese capital.
“But every tournament is a different story so you gotta start from the beginning and grind.”
World number five Mirra Andreeva of Russia swept aside Zhu Lin of China 6-2, 6-2 and American Jessica Pegula dispatched Australian Ajla Tomljanovic 6-0, 6-3. (AFP)
