Novak Djokovic withdraws from Serbia Open

World number one Novak Djokovic has pulled out of the Serbia Open following the recent death of his grandfather.

As a result, the 24-year-old will not defend the crown that he won in Belgrade last year.

"I've made a decision not to take part in the tournament this year," Djokovic wrote on his official website.

"This is certainly one of the toughest decisions in my career but it is impossible for me to play in the next few days and to think about tennis when there are some other things in my head."

The tournament is organised by Djokovic's uncle Goran.