Paris - American seventh seed Sloane Stephens reached the Roland Garros quarter-finals for the second successive year on Sunday with a 6-4, 6-3 win over 2016 champion Garbine Muguruza.
Stephens will face Johanna Konta, the first British woman in the last-eight since 1983, for a place in the semi-finals.
The 26th seed had been a break down early in the first set but recovered and claimed victory on a fifth match point.
Results from the eighth day of the French Open on Sunday (x denotes seeding):
Stan Wawrinka (SUI x24) bt Stefanos Tsitsipas (GRE x6) 7-6 (8/6), 5-7, 6-4, 3-6, 8-6
Roger Federer (SUI x3) bt Leonardo Mayer (ARG) 6-2, 6-3, 6-3
Kei Nishikori (JPN x7) leads Benoit Paire (FRA) 6-2, 6-7 (8/10), 6-2 - match suspended due to darkness
Rafael Nadal (ESP x2) bt Juan Ignacio Londero (ARG) 6-2, 6-3, 6-3
Sloane Stephens (USA x7) bt Garbine Muguruza (ESP x19) 6-4, 6-3
Johanna Konta (GBR x26) bt Donna Vekic (CRO x23) 6-2, 6-4
Marketa Vondrousova (CZE) bt Anastasija Sevastova (LAT x12) 6-2, 6-0
Petra Martic (CRO x31) bt Kaia Kanepi (EST) 5-7, 6-2, 6-4