Novak Djokovic courted controversy on Monday when he wrote “Kosovo is the heart of Serbia. Stop the violence” on a camera at the French Open after clashes flared in northern Kosovo amid ethnic tensions. 

The Belgrade-born tennis superstar wrote the message in Serbian after his opening round victory over Aleksandar Kovacevic 6-3, 6-2, 7-6 (1) on the showpiece Philippe Chatrier Court at Roland Garros.