Rafael Nadal of Spain in action against Novak Djokovic of Serbia during the men’s singles final match for the China Open tennis tournament at the National Tennis Center in Beijing, China, 11 October 2015. EPA/WU HONG

Novak Djokovic of Serbia in action against Rafael Nadal of Spain during the men’s singles final match for the China Open tennis tournament at the National Tennis Center in Beijing, China, 11 October 2015. EPA/HOW HWEE YOUNG

Novak Djokovic of Serbia in action against Rafael Nadal of Spain during the men’s singles final match for the China Open tennis tournament at the National Tennis Center in Beijing, China, 11 October 2015. EPA/HOW HWEE YOUNG

Rafael Nadal of Spain in action against Novak Djokovic of Serbia during the men’s singles final match for the China Open tennis tournament at the National Tennis Center in Beijing, China, 11 October 2015. EPA/HOW HWEE YOUNG

Rafael Nadal of Spain in action against Novak Djokovic of Serbia during the men’s singles final match for the China Open tennis tournament at the National Tennis Center in Beijing, China, 11 October 2015. EPA/WU HONG

Winner Novak Djokovic (R) of Serbia and runner up Rafael Nadal of Spain pose with their trophies during the awarding ceremony of the men’s singles final match in the China Open tennis tournament at the National Tennis Center in Beijing, China, 11 October 2015. EPA/HOW HWEE YOUNG