Iga Swiatek had to negotiate a rare second-set dip to extend her winning streak and take another step towards her second French Open title.
The world number one seemed to be cruising into round four as she led 6-3 4-1, with two breaks of serve, against Danka Kovinic of Montenegro.
But four games later Kovinic, ranked 95 in the world, had hit back to lead 5-4.
Swiatek managed to reset and claim a 6-3 7-5 victory for a 31st consecutive win.
“I wanted to play really aggressively but sometimes I feel I was putting in too much power and it was hard to control it,” she said.
“I needed to play with a little less risk and be more consistent.
“She did a pretty good job of defending and giving back at full speed.
“She was serving really precisely – it was a little tricky but I have played with some heavy hitters already, but it was pretty hard to adjust at the beginning.
“I feel like I can play more fearlessly but today I lost both the breaks. But playing well at the beginning is putting pressure on my opponents, which is important.”
Romania’s Irina-Camelia Begu ended the fairytale run of French wildcard Leolia Jeanjean with a 6-1 6-4 win.
Jeanjean, ranked 227 in the world, had stunned eighth seed Karolina Pliskova in the second round.
The 26-year-old lived on the minimum wage after a knee injury forced her to give up tennis for almost five years, but her decision to return paid off handsomely as she will pocket around £107,000 in prize money.
Fellow French player Alize Cornet had to tearfully retire injured at 6-0 3-0 down to 19-year-old Qinwen Zheng from China.
