Three-time Grand Slam champion Angelique Kerber has lost in the first round of the French Open for the second straight year.
19-year-old Slovenian Kaja Juvan beat the 18th-seeded German 6-3, 6-3.
Kerber held the no.1 ranking. He has won every major title except the French Open. Her best performances were the quarterfinals at Roland Garros in 2012 and 2018.
Garbine Muguruza could have joined Kerber and Kuznetsova.
But the 2016 French Open champion held firm to beat Tamara Zidansek 7-5, 4-6, 8-6.