Iga Swiatek continued the defence of her French Open crown on Monday night with a hard fought 6-3, 6-4 victory over the unseeded Ukrainian teenager Marta Kostyuk.
Kostyuk accounted for the 2016 champion Garbine Muguruza in the first round and she made it clear from the opening exchanges she was unfazed about adding another illustrious name to her pile of victims.
Her powerful clean hitting brought her the first break of the match but she was reeled in and Swiatek got the decisive one to lead 5-3.
The 20-year-old Pole claimed it on her third set point after 50 bruising minutes when a Kostyuk backhand flew long.
Swiatek fashioned the first opening of the second set. And Kostyuk's third double fault gave Swiatek a break for a 2-1 lead. But she came right back for 2-2.
At 3-3 Swiatek took the second of her opportunities to seize Kostyuk's serve as the hitting veered from savage to ragged.
Swiatek held for 5-3 after saving a break point.
And she got her first match point when a Kostyuk backhand hit the net cord and back onto her side of the court.
Kostyuk saved bravely with a fifth forehand winner and she eventually held forcing Swiatek to serve for the tie at 5-4.
Swiatek's surge to glory did not start well. She lost the first two points but clawed her way back to reach match point.
And she claimed a place in the last eight with a volleyed lob over a stranded Kostyuk.
"She defended incredibly well and it was difficult to win a point," said Swiatek.
"I'm proud to get through. Reaching a quarter final of the Gand Slam tournament doesn't happen every day."
At eight, Swiatek is the highest ranked seed remaining in the draw.
She will next play the 17th seed Maria Sakkari who took out last year's finalist Sofia Kenin.
Sakkari beat the fourth seed 6-1, 6-3 to become the first Greek woman to reach the last eight at a Grand Slam tournament.
The unseeded Czech Barbora Krejcikova and 17-year-old Cori Gauff also advanced to their first Grand Slam quarter-final after wins over Sloane Stephens and Ons Jabeur respectively.