The world No.8 continued her career-best run at Roland Garros on Saturday (Sunday morning AEST) with a 6-3 6-1 win in just an hour.

It was the first meeting between Barty and Petkovic with the Queenslander breaking the former world No.9 four times out of six break points.

Barty had 20 winners to 11 unforced errors in the tilt, while Petkovic's nine winners were negated by her 24 unforced errors.

The Australian will now face Sofia Kenin, who upset three-time champion Serena Williams, 6-2, 7-5, to book her first-ever fourth-round appearance at a Grand Slam event.

If she is able to overcome Kenin on Monday she could face either American Madison Keys or Czech Kateřina Siniakova, who beat Naomi Osaka.

Barty is the highest-remaining seeded player in the top quarter of the draw after Osaka's exit. 

She will be back on court on Sunday for her doubles clash with Victoria Azarenka against Belinda Bencic and Viktória Kužmová.

There was also a win for another Aussie on Saturday as Sam Stosur and Zhang Shuai continued their Grand Slam success in doubles with a 6-4 6-4 victory over American duo Danielle Collins and Sabrina Santamaria.