World No. 1 Novak Djokovic was reduced to tears after suffering a shock first round 7-6(4) 7-6(2) loss to Argentina’s Juan Martin del Potro in the men’s Olympic tennis tournament on Sunday.Djokovic has dominated the men’s game in recent years and had made it a priority to win an Olympic gold medal, the only major prize that still eludes him.“No doubt this is one of the toughest losses in my life and in my career,” a distraught Djokovic told reporters.“It’s not easy to handle, especially now, just after the wounds are still fresh.”After winning this year’s Australian and French Open titles, Djokovic was the favourite to add Olympic gold to his 12 grand slam titles and Del Potro was as surprised as anyone to see the Serb go out.“I didn’t expect to beat Novak tonight,” said the 2009 U.S. Open champion, who has been battling a wrist injury for much of the season and is ranked 141st in the world.“But I played an amazing match, my forehand worked great.”The 27-year-old Argentine crunched 29 forehand winners in comparison to just seven by Djokovic, who lost a bronze medal match to Del Porto at the London Olympics four years ago.Del Potro, who was once ranked fourth highest in the world, said the performance against Djokovic gave him hope of fully overcoming his injury nightmare.“I felt once again I had the capability to play against the best in the world,” he said.“This kind of atmosphere I experience a few times in my life, mostly when I’m in my country. This felt like I was in my country. This felt like I was Brazilian,” said Djokovic.The Serb will get another chance to experience the Rio atmosphere when he teams up with Nenad Zimonjic to play Brazilian duo Marcelo Melo and Bruno Soares in a second round men’s doubles match on Monday.