The Djokovic family did not enjoy any success at their home tournament this year.
With defending champion and top-ranked Novak Djokovic having pulled out of the event, his brother Marko lost in the first round to Filippo Volandri at the Serbia Open on Monday.
Marko Djokovic, a wild-card-entry, was broken four times and never forced a break point of his own before losing 6-3 6-1 in one hour.
The tournament is organised by the Djokovic family, but Novak pulled out because of the recent death of his grandfather – a decision he called one of the hardest of his career.
In other first-round matches on Monday, Dusan Lajovic of Serbia defeated fellow wild-card entry Evgeny Donskoy of Russia 7-5 6-4, and Ivan Dodig used six breaks of serve to overcome Adrian Ungur of Romania 6-2 6-7 (7-4) 6-4.