Serena Williams exited the French Open on Saturday to her fellow American Sofia Kenin in the third round.
Williams, bidding for a 24th major, rallied in a second set but fell 6-2 7-5. A knee injury hampered the 37-year-old in the buildup.
Kenin, a hard-hitting baseliner, celebrated victory. The 20-year-old made the fourth round at a major for the first time.
It was indeed a day of shocks, as Naomi Osaka saw her 16-match grand slam winning streak come to an end.
The world No. 1 lost in straight sets to Katerina Siniakova, going 0-for-7 on break points and making 38 unforced errors.
Siniakova, 23, is a doubles world No. 1 and former junior star. She picked up her first win over a No. 1 player in singles.
After dropping a set in her first two matches, defending champion Simona Halep needed just an hour to breeze past Lesia Tsurenko.
Men's No. 1 Novak Djokovic continued to cruise. The Serb, bidding for a fourth straight major, beat Italy's Salvatore Caruso 6-3 6-3 6-2.
Stan Wawrinka, the 2015 champion, collected his 500th career win when he completed a 7-6 7-6 7-6 win over Grigor Dimitrov. The match had been suspended due to darkness Friday after two sets.
Stefanos Tsitsipas, semifinalist at the Australian Open and a winner over Rafael Nadal on clay last month, continued to progress with a four-set win over Filip Krajinovic.