Ball children prepare during the French Open tennis tournament at Roland Garros in Paris, France, 27 May 2015. EPA/ROBERT GHEMENT

A ballboy during Novak Djokovic of Serbia against Jarkko Nieminen of Finland during their first round match for the French Open tennis tournament at Roland Garros in Paris, France, 26 May 2015. EPA/ROBERT GHEMENT

Ball children in action during the match Alize Cornet of France against Roberta Vinci of Italy during their first round match for the French Open tennis tournament at Roland Garros in Paris, France, 25 May 2015. EPA/ROBERT GHEMENT

A ball girl in action during the first round match between Roberta Vinci of Italy in action against Alize Cornet of France during for the French Open tennis tournament at Roland Garros in Paris, France, 25 May 2015. EPA/ROBERT GHEMENT

Ball children rest during the French Open tennis tournament at Roland Garros in Paris, France, 27 May 2015. EPA/ROBERT GHEMENT