Heather Watson and Kyle Edmund reach second round at Rio Olympics

There were contrasting victories for Britons Kyle Edmund and Heather Watson on the opening day of tennis action at the Rio Olympics.

While Edmund cruised past Aussie Jordan Thompson 6-4 6-2, Watson needed three sets to see off Shuai Peng of China in a contest that lasted two and a half hours.

Watson won 6-4 6-7 (5-7) 6-3, having missed the opportunity to clinch a straight-sets triumph when she served for the match at 6-5 in the second.

The final set yielded five breaks of serve, with world No 67 Watson securing a hard fought triumph on her third match point.

Watson, who four years ago lost in round two, admitted: "It was a toughie. I didn't play my best.

"I don't think it was the prettiest of matches but it was one of those winning ugly ones and in the third set I think it was a battle of the fittest and I actually felt great, so I'm really pleased with that."

The Guernsey player had not won a singles since the Birmingham grass court event in June, and her reward for beating the world No 264 Peng is a second round clash with the No 15 seed Elina Svitolina from Ukraine.

As for Edmund, he needed just 73 minutes to wrap up a contest in which he denied his opponent a single break point.

Edmund added: "It's just nice to get the win really. There's been quite a lot of training since my last match in Toronto so you just want to get going.

"I didn't feel that nervous, just excited. It's nice to put on the GB shirt. It's not something you get to do all the time."

Next up for Edmund is Japan's Taro Daniel, with Novak Djokovic potentially lying in wait should they both progress to the third round.

Meanwhile, there was a shock defeat for the No 4 seed Agnieszka Radwanska in the women's singles.

The Pole was beaten 6-4 7-5 by China's world No 64, having had to fly more than 14,000 km - via Montreal, New York and Lisbon - to reach Rio.

Radwanska said: "I spent three days in an airport, so that was not the best preparation. I could have used more practice."

Elsewhere, former French Open winner Ana Ivanovic lost 2-6 6-1 6-2 to the ninth seed Carla Suarez Navarro of Spain.

In other men's matches, the No 4 seed Kei Nishikori opened proceedings on Saturday with a 6-2 6-4 win over Albert Ramos-Violas of Spain.

And Marin Cilic's potentially tricky encounter with Bulgarian Grigor Dimitrov was anything just, as the Croatian eased to a 6-1 6-4 victory in just over an hour.