Williams sisters in shock doubles loss

Three-time doubles gold medallists Serena and Venus Williams lost an Olympic match as partners for the first time, stunned in the opening round of the Rio de Janeiro Games by the Czech Republic's Lucie Safarova and Barbora Strycova 6-3 6-4.

The Williams sisters entered Sunday's match with a 15-0 career record in the Olympics, winning the gold medal in women's doubles every time they entered the event: in 2000, 2008 and 2012.

"We played terrible," Serena said, "and it showed in the results."

The American duo was seeded No.1 in Rio and coming off a 14th grand slam championship together at Wimbledon a month ago.

Neither Safarova nor Strycova, meanwhile, ever had won an Olympic doubles match, going a combined 0-3 with other partners. They are unseeded in Rio.

And get this: They weren't even supposed to be playing together at the Olympics. Strycova was a late replacement for Karolina Pliskova, who withdrew from the tournament.

Indeed, Strycova and Safarova only had played one match as a team before Sunday night - and they lost that, in a Fed Cup match last year.

Still, Strycova said: "We're good friends, and we know each other's games."

This was Serena's second match of the day: She won her first-rounder in singles earlier Sunday against Australian Daria Gavrilova. Venus, meanwhile, now has two first-round exits at the Rio Olympics, because she was beaten in singles on Saturday night.