Serbian hero Novak Djokovic will not defend his title next week at the Serbia Open, a tournament organized by his family, because of the death of his grandfather last week.

The world No. 1 star lost badly to former top-ranked stalwart Rafael Nadal in last week's finale at the Monte Carlo Masters, with the passing of his grandfather weighing heavily on his mind at the time.

Djokovic said he is emotionally drained since his grandfather died last Thursday.

"This was one of the most difficult decisions in my career, but it is impossible for me to play and think about tennis," Djokovic said.