Novak Djokovic’s bid to win an Olympic men’s singles title will have to wait another four years after the Serbian superstar fell 7-6 7-6 to 141st-ranked Argentine, Juan Martin del Potro in the first round in Rio 2016.
The world number one has now lost to del Potro in back-to-back Olympics, after the giant Argentine overpowered the Serbian in the bronze-medal match in London four years ago.
The 29-year-old Djokovic was in tears as he left the court after the match, which he described as one of the toughest losses in his career.
It was a great moment for 2009 US Open champion, del Potro, who has only just returned to the tour after two years of injury problems.
He will face Portugal’s Joao Sousa in the second round on Monday.
Elsewhere, second seed, Andy Murray made light work of Serbia’s Victor Troicki in a 6-3 6-2 victory, while Rafael Nadal marked his return from a wrist injury with a 6-2 6-1 dispatch of Argentine, Federico Delbonis.