Rio 2016 Olympics - World number one Novak Djokovic was dumped out of the Rio Games in the first round by Argentina's Juan Martin del Potro, a shock result that reduced the Serb to tears as he left the court.
Djokovic, who won this year's Australian and French Open titles, 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 del Potro, who has been battling a wrist injury for much of the season.
"But I played an amazing match, my forehand worked great."
Del Potro used his lethal forehand to stun the Serb with a powerful display to win 7-6(4) 7-6(2) in the biggest upset of the tennis tournament.
Earlier in the day, del Potro briefly got stuck in a malfunctioning lift but his luck improved against Djokovic, whom he also defeated in the bronze medal match at the London Games.
Del Potro has fallen outside the top 100 in the world rankings but showed flashes of the hard-hitting brilliance that helped him win the US Open in 2009.
Earlier in the day American tennis stars Serena and Venus Williams crashed out in the first round of the women's doubles in Rio.
It is the first time the duo have lost an Olympic doubles match.
The pair were dumped out by Czech pair Barbora Strycova and Lucie Safarova in straight sets.
The Williams sisters won the women's doubles title at the Sydney 2000, Beijing 2008 and London 2012 Games.
The New Zealand men's doubles pairing of Marcus Daniell and Michael Venus lost their first round Olympic match 6-4,3-6,6-7 against Canada in Rio.