Paris: Sixth seed Samantha Stosur reached the last 16 of the French Open on Friday, defeating an erratic Nadia Petrova of Russia 6-3, 6-3 in the third round. (Agencies)
US Open champion Stosur, 28, will play 19-year-old American Sloane Stephens for a place in the quarter-finals.
Petrova, a former world number three, had a 5-2 record against Stosur going into the match.
Unfazed by their head-to-head numbers, Stosur raced to 4-0 in the first set with two breaks, but Petrova broke back in the fifth game and then held serve to stay within striking distance.
Stosur, the runner-up at Roland Garros in 2010 to Italy's Francesca Schiavone, regained her composure and finished off the first set with a forehand winner.
In the second set, 27th-seed Petrova, who turns 30 next week, looked set to put up a challenge until she gave away the third game with a double fault.
Stosur was nearly broken in the next game but rallied back to stay ahead at 3-1 and used pinpoint playmaking to keep the sluggish-looking Petrova at a distance, finally sealing the match with a backhand winner down the line.
Their last two encounters, which they split one apiece, had gone the distance and ended in tiebreaks, but Friday's match was one-sided from the start as Stosur pressed ahead with her bid for a second Slam.
Paris: Sixth seed Samantha Stosur reached the last 16 of the French Open on Friday, defeating an erratic Nadia Petrova of Russia 6-3, 6-3 in the third round.