World number one Novak Djokovic was defeated by his fellow Serbian Dusan Lajovic in Srpska Open quarterfinals on Friday evening.

The 6-4 7-6 defeat comes a week after last week's surprise defeat at Monte Carlo Masters, when Djokovic said he was “not really in the mood to speak” to reporters.

Earlier this week, the world's best tennis player complained that he was struggling with his right elbow.

In Banja Luka, Djokovic entered the match poorly, which Lajovic used in his favour and won a break, which led him to winning the first set.

Although Djokovic improved his performance in the second match, Lajovic kept up with him and was better in the tie-break, finishing the second set in his favour and winning the match.

Speaking to reporters after the match, the winner said this was the “greatest victory of his career.

“I have mixed feelings, he is our country's hero, I never thought it was possible to win against him,” said Lajovic, who thanked the audience for the support.

Djokovic briefly addressed the media, praising his opponent's performance but admitting that he wasn't playing well himself.

“I tried, it didn't work. I didn't feel physically well. At times I played well, but generally quite below the level,” said Djokovic.