Olympic champion and world number one Serena Williams tumbled out of the Rio de Janeiro singles competition in the third round on Tuesday after a shock defeat to Ukraine's Elina Svitolina.
Svitolina, ranked 20 in the world, stunned the London Games gold medallist 6-4, 6-3 to record a memorable victory against the American, who has won 22 Grand Slam singles titles.
With this loss, Serena misses a chance to claim her 5th Olympic gold.
French Open champion Muguruza crashes out
Puerto Rico's Monica Puig collapsed in tears of joy after her shock 6-1, 6-1 win over Spain's French Open champion Garbine Muguruza.
Puig, ranked 34 in the world, said the victory against third seed Muguruza was the biggest win in her career.
"I still have goosebumps," said Puig, who will play Germany's Laura Siegemund in the quarter-finals.
"I already know where I want to get and I'm letting the world know that I’ve arrived."
Muguruza, who lost in the second round at Wimbledon, said she was surprised by the intensity and quality of play by 22-year-old Puig.
"I was very shocked about how she played today. I think she played unbelievable. Also I didn't find the way tactically to beat her," she told reporters.
World number two and Australian Open champion Angelique Kerber faced fewer surprises in her match against Australia's Samantha Stosur, with the German triumphing 6-0, 7-5 on way to a quarter-final meeting with Britain's Johanna Konta.
Murray, Nadal sail through
The highest seeds remaining in the men's tournament, Andy Murray and Rafael Nadal, progressed into the third round with ease.
Murray, who won singles gold at his home Games in London, outclassed Argentina's Juan Monaco 6-3, 6-1 and will next face Italy's Fabio Fognini.
"I played pretty well, hit the ball good from the back of the court, not many unforced errors. It was a good match," said Murray, who is favorite to defend his title after Serbian world number one Novak Djokovic was eliminated in the first round.
The 2008 Olympic gold medalist Nadal overpowered Italy's Seppi Andreas 6-3, 6-3 despite admitting over the weekend that he was still not fully fit.
"It was important to be playing like this. I’m enjoying (myself), I’m happy on the court," the Spanish third seed said.