American Sloane Stephens gave an indication of her French Open ambitions, defeating No.18 Karolina Muchova of the Czech Republic 6-3, 7-5 in one hour, 55 minutes to move into the pre-quarterfinals on Saturday.
The 2018 runner-up will next face another Czech player, world No.33 Barbora Krejcikova, who had won her maiden title in Strasbourg last week to signal her intent.
Barbora extended her winning streak to eight, thrashing No.6 seed Elina Svitolina of Ukraine 6-3, 6-2.
Karolina and Elina's exit means the only seeds remaining in the top quarter of the draw are No.13 Jennifer Brady, No.24 Coco Gauff (both US) and No.25 Ons Jabeur (Tunisia).
Sloane, who has now reached the fourth round on seven of her 10 appearances at Roland Garros, was in control of the proceedings from the start, taking a 6-3, 2-0 lead.
The world No. 59 American got 84 per cent of her first serves in and, combining it with aggressive play, left Karolina clueless.
Though Karolina did come up with occasional winners, the Czech player was unable to consistently trouble Sloane.