John Isner of the USA in action against Kyle Edmund of Britain during their men’s single second round match at the French Open tennis tournament at Roland Garros in Paris, France, 25 May 2016. EPA/Christophe Petit Tesson

Andy Murray of Britain in action against Mathias Bourgue of France during their men’s single second round match at the French Open tennis tournament at Roland Garros in Paris, France, 25 May 2016. EPA/YOAN VALAT

Simona Halep of Romania in action against Zarina Diyas of Kazakhstan during their women’s single second round match at the French Open tennis tournament at Roland Garros in Paris, France, 25 May 2016. EPA/ROBERT GHEMENT

Alexander Zverev of Germany in action against Pierre-Hugues Herbert of France during their men’s single first round match at the French Open tennis tournament at Roland Garros in Paris, France, 24 May 2016. EPA/ETIENNE LAURENT

Fernando Verdasco of Spain in action against Ivan Dodig of Croatia during their men’s single second round match at the French Open tennis tournament at Roland Garros in Paris, France, 25 May 2016. EPA/Christophe Petit Tesson