Serena Williams and Johanna Konta both advance at Olympics

Top seed Serena Williams and British No 1 Johanna Konta both enjoyed straight sets victories in their opening matches at the Rio Olympics.

But there was a big upset in the doubles, as Serena and her sister Venus were knocked out by Czech duo Lucie Safarova and Barbora Strycova.

In the singles, Serena began her quest for a second successive Olympic title with a comfortable triumph over Aussie Daria Gavrilova, while Konta eased past Stephanie Vogt of Liechtenstein.

The world No 1 American needed 93 minutes to wrap up a 6-4 6-2 win and, despite being broken twice in the opening set, the 34-year-old took charge and secured a straight sets triumph on her third match point.

Strong gusts prevented matches on some courts from starting on time and Williams was relieved to have made it through.

She said: "It was really intense. I think my last Olympic final four years ago was really windy too.

"Today they couldn't start the matches on the outside courts. I was a little nervous about that so I was happy to get through."

Konta, meanwhile, won 6-3 6-1 in 77 minutes by taking 11 of the final 13 games. 

She is thoroughly enjoying the Olympic experience and said: "It's been great, it's nothing like anything else. I'm really
enjoying being able to chat to the hockey guys or the rugby girls.

"I've made it my mission to become more informed about the other sports, because I'm definitely not impressed with how little knowledge I have."

Also through is the No 2 seed Angelique Kerber who recovered from 2-5 down in the second set to beat Mariana Duque-Marino of Colombia 6-3 7-5.

The German now faces Canada's Eugenie Bouchard, the Wimbledon runner-up in 2014.

Kerber was also concerned about the conditions in Rio: "When I practiced at 9 o'clock this morning, it was 35 degrees and then we had two hours' delay.

"Then the wind came, it was cloudy and cooler."

Another winner on Sunday was two-time Wimbledon champion Petra Kvitova who breezed past Hungary's Timea Babos.

The big-serving Czech, seeded 11, won 6-1 6-2 and will now take on Caroline Wozniacki in a stand-out second round clash.

There was drama in the doubles later on, when top seeds and three-time former champions Venus and Serena were defeated 6-3 6-4 by Safarova and Strycova.

It was the sisters' first loss as a doubles team at the Games, having won 15 previous matches together, taking the title in 2000, 2008 and 2012.

"It was not our best day," said Venus. "We like to have a chance to play our way into the tournament but we came up against a very strong team.

"We wish them the best of luck and we'll get ready for the US Open."