Angelique Kerber suffered a shock first-round defeat on the opening day of the French Open.
The number-five seed went down to 18-year-old Anastasia Potapova in straight sets, 6-4, 6-2.
Kerber, the reigning Wimbledon champion, was aiming to complete her career slam at Roland Garros.
2016 winner Garbine Muguruza came from a set down to beat Taylor Townsend 5-7 6-2 6-2, while in the men's draw Stefanos Tsitsipas and Marin Cilic both progressed to the second round with straight sets wins over Maximilian Marterer and Thomas Fabbiano respectively.
South Africa 69 runs away from winning World Test Championship
Saudi Arabia, Qatar to host fourth round of Asia's World Cup qualifiers
Big target looms but South Africa are confident of chasing it down
De Bruyne joins Italian champions Napoli after Man City exit
Australia topple S Africa top order to take charge of WTC final
