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.
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