Serena and Venus Williams, three-time women's doubles Olympic champions, crashed out in the first round at the Rio Games on Sunday in one of the biggest upsets so far in women's tennis.
The Williams sisters were beaten by the Czech Republic pair of Barbora Strycova and Lucie Safarova 3-6, 4-6.
They bagged their first women's doubles title at the 2000 Sydney Games and repeated the feat at the 2008 Beijing and 2012 London Games.
Going into the match with a 15-0 career record in the Olympics, they were seeded No. 1 and coming off a 14th Grand Slam championship together at Wimbledon a month ago.
Neither Safarova nor Strycova, unseeded at the Games, had won an Olympic doubles match, going a combined 0-3 with other partners.
They played just one match as a team before, at the Fed Cup match last year, and lost it.