Stephens will face the winner of the fourth-round match between second-seeded Caroline Wozniacki and 14th-seeded Daria Kasatkina, which was halted at 9:22 p.m. on Sunday because of darkness and will resume on Monday afternoon.
Keys will face Yulia Putintseva, a fiery Russian-turned-Kazakh who beat 26th-seeded Barbora Strycova 6-4, 6-3.
Keys’s newfound clarity on clay will be tested against Putintseva, who can drive even the calmest players to distraction with her emotive outbursts. Strycova, herself one of the game’s most expressive players, said she struggled to tune out Putintseva’s draining dramaturgy, which she believes Putintseva exaggerates to disrupt an opponent’s rhythm.
“My coach told me before the match that I have to focus on myself, which I tried to do,” Strycova said. “But she screams sometimes hard for the balls where I’m like, ‘This is just weird?’ But I guess she needs it — and she plays well when she does that.”
Putintseva, ranked 98th, reached the quarterfinals once before, in 2016, coming within five points of beating the top-seeded Serena Williams in that match.
Williams herself will be looking to rejoin Putintseva in the last eight on Monday, when she faces Maria Sharapova in a blockbuster fourth-round encounter. Williams and her sister Venus were eliminated in the third round of the doubles draw on Sunday, falling 6-4, 6-7(4), 6-0 to the third-seeded pair of Andreja Klepac and Maria Jose Martinez Sanchez.