Tennis current world No. 1 Novak Djokovic of Serbia suffered a stunning upset after world No.55 Jiri Vesely of the Czech Republic defeated the tournament's defending champion 4-6, 6-2, 4-6 in the second round of the  ATP 2016 Monte Carlo Masters in Monaco on Wednesday.

The 11-time Grand Slam singles titlist failed to mount a recovery against the 22-year-old Czech professional tennis player, who got the upper hand after claiming the opening set of the match. The loss was Djokovic's second of the season and the Serbian's earliest defeat on the ATP World Tour in three years.

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"Obviously it's not easy to lose the match in terms of accepting it right after exiting the court. But I have to congratulate my opponent," Djokovic, who bowed out to a player ranking outside the Top 50 for the first time since enduring a defeat to the then world No. 74 Xavier Malisse in 2010, said. "I think he played very solid. He was serving very big. He was playing tactically good and aggressive."

Vesely, who was a gold medalist in the 2010 Summer Youth Olympics in the boy's double event held in Singapore, held his nerve for a shocking upset in two hours and six minutes. He was denied a match point as the world's top tennis player held serve in the ninth game to force the Czech to serve it out. The left-handed Vesely did not stumble and served out the win to 15 in the succeeding game.

"I'm just very, very happy," Vesely, who has won just one match in the seven tournaments that he participated since the start of the season, said. "When I went on court, I had completely different thinking, like, 'I hope to win a game,' or 'I really hope to do well.' But I really had no idea that I really would be able to beat Novak today."

Vesely will be facing the 13^th seeded and world No. 16 Frenchman Gael Monfils, who defeated the Italy's world No. 53 Paolo Lorenzi 6-2, 6-4, for the quarterfinals berth.

Tagsnovak djocovic, jiri vesely, ATP Tour news, atp 2016, atp rankings, Monte Carlo Masters