But she is optimistic she can capitalise on an established superiority over Stephens - she leads the rivalry 5-2 - in a watershed encounter.
"I obviously lost to Sloane at the US Open, but I feel like on clay it's a little bit of a different match-up", Keys said.
After the 13th-seeded Keys held for 5-4, Stephens served out victory at the second attempt. The Russian-born, Florida-based Kazakh player took exception to just one service call and smiled warmly at Keys when they shook hands over the net.
The 10th seed, who beat Keys to win the U.S. Open last year, showed impressive patience in some cat-and-mouse exchanges and eventually overpowered the 21-year-old with her bigger game.
He also says Sharapova's confidence is high ahead of her quarterfinal appearance in her first French Open since her return from a 15-month doping ban.
Earlier, Keys advanced to her first French Open semifinal by defeating Yulia Putintseva 7-6 (5), 6-4. The Romanian also came up one victory shy of a major championship at the Australian Open in January, beaten there by Caroline Wozniacki.
Keys and Stephens could potentially face off in the semi-finals, if the former gets past Putintseva, and the latter overcomes Daria Kasatkina in the last-eight.
Novak Djokovic found himself two sets down against Marco Cecchinato, losing the second set 7-6 (4) in a tiebreak. "That's why I got angry with someone".
Halep, who lost in last year's final, broke the 16th-seeded Belgian's serve six times on Court Philippe Chatrier. He then moved even closer to them and began verbally confronting a man. "I obviously rely on what I learned there and how to manage my emotions and manage the moment, but there were so many late nights and I was so exhausted".
He has no trouble identifying his semifinal opponent: Rafael Nadal. "That means one American will be in the final of a French Open, which is another awesome thing".
Twice the runner-up in Paris, Halep has qualified for the final by defeating 2016 champion Garbine Muguruza 6-1, 6-4. But she had since talked about the burden she felt while playing the sport.
Simona Halep is hoping to win her first grand slam title on Saturday in Paris.
No. 1 Simona Halep vs. This is Robinson's 19th French Open for NBC. The 12-time Grand Slam victor fought through a bothersome neck and right leg before falling to Cecchinato, who before Monday was most well-known for a match-fixing suspension that was eventually overturned on appeal.
Halep is a three-time Grand Slam runner-up, including in Paris in 2014 and a year ago; Kerber is a two-time major champ elsewhere; Muguruza won the French Open in 2016 and Wimbledon in 2017; and Sharapova owns five Grand Slam titles, including at Roland Garros in 2012 and 2014.