American Madison Keys beat Katerina Siniakova in straight sets to set up a French Open quarter-final against Australian eighth seed Ashleigh Barty.
Keys, a semi-finalist at Roland Garros last year, progressed in one hour 16 minutes with a 6-2 6-4 victory over the 23-year-old Czech.
Barty, meanwhile, needed three sets to see off American Sofia Kenin, 20, who previously knocked out Serena Williams.
Barty eventually won 6-3 3-6 6-0 on Court Philippe Chatrier.
It means a first quarter-final in Paris for the 23-year-old and her second in as many Grand Slams this year, after reaching the last eight at the Australian Open.
