Rain delays the matches at the French Open tennis tournament at Roland Garros in Paris, France, 23 May 2016. EPA/ROBERT GHEMENT

Stan Wawrinka of Switzerland in action against Lukas Rosol of Czech Republic during their men’s single first round match at the French Open tennis tournament at Roland Garros in Paris, France, 23 May 2016. EPA/ETIENNE LAURENT

Sabine Lisicki of Germany in action against Veronica Cepede Royg of Paraguay during their women’s single first round match at the French Open tennis tournament at Roland Garros in Paris, France, 23 May 2016. EPA/YOAN VALAT

Ball girl and boy run as Jeremy Chardy of France plays against Leonardo Mayer of Argentina during their men’s single first round match at the French Open tennis tournament at Roland Garros in Paris, France, 23 May 2016. EPA/Christophe Petit Tesson

Garbine Muguruza of Spain in action against Anna Karolina Schmiedlova of Slovakia during their women’s single first round match at the French Open tennis tournament at Roland Garros in Paris, France, 23 May 2016. EPA/ROBERT GHEMENT

Leonardo Mayer of Argentina in action against Jeremy Chardy of France during their men’s single first round match at the French Open tennis tournament at Roland Garros in Paris, France, 23 May 2016. EPA/Christophe Petit Tesson