World No. 1 Novak Djokovic has pulled out of the Serbia Open tennis following the death of his grandfather during the Monte Carlo Masters event last week.
"I've made a decision not to take part in the tournament this year," Djokovic, the title holder at the Belgrade claycourt event, said on his 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 world number one said he had "no emotional energy left" after being thrashed by Rafael Nadal in the Monte Carlo final on Sunday, and would be back in action at the Madrid Masters, which starts on May 6.
The April 30-May 6 Serbia Open is organised by Djokovic's uncle Goran.