JOHANNA KONTA'S victory over Caroline Garcia was the only bright spot to be found for Great Britain on the third day of action at the Olympic Tennis Centre.
Konta eased past France's Garcia 6-2 6-3 to reach the third round but there were singles defeats for Heather Watson and Kyle Edmund while Konta and Watson lost in the second round of the doubles.
An early break of serve put 10th seed Konta in control of the first set and another helped the 25-year-old seal it in 38 minutes as Garcia became increasingly frustrated.
Read more: Novak Djokovic suffers second defeat at Rio Olympics as he exits doubles
Konta broke Garcia's serve three more times in the second set and, although the Frenchwoman did retrieve one of the breaks, it was to no avail as Konta set up a meeting with eighth seed Svetlana Kuznetsova in the last 16.
"I'm very happy I was able to stay tough in the close and long games," said Konta. "Kuznetsova's a great player and had a very good year so far. I'm going to have a very tough match and will go out there and do my best."
Watson had a tough task against 15th seed Elina Svitolina.
She recovered from losing the first set to race through the second in 28 minutes for the lost of just one game, but Svitolina took her only break point in the decider to seal a 6-3 1-6 6-3 victory in an hour and 47 minutes.
"It was very disappointing for me," the 24-year-old from Guernsey said. "I have played her twice and beaten her twice. Both have been close three-set matches and I wasn't surprised this one went to a third as well.
"I wasn't feeling my best physically but after that first set I started to feel a lot better and more in the match and I definitely had my opportunities early in that third set but wasn't able to take them."
Watson and Konta were up against third-seeded sisters Chan Yung-jan and Chan Hao-ching from Chinese Taipei in the doubles.
After taking the opening set they lost eight straight games but recovered to lead 4-3 with a break in the decider only for the Chans to come through 3-6 6-0 6-4.
Edmund had earlier suffered a disappointing defeat to Japan's Taro Daniel in the second round of the men's singles.
The British number two is ranked 36 places higher than world number 117 Daniel but could not find his best form on the slow courts and went down 6-4 7-5.
Edmund, Britain's Davis Cup hero last month, led by a break in both sets but was unable to penetrate Daniel's defences on enough occasions and made too many sloppy errors.
The 21-year-old Yorkshireman said: "It was a tight match, some long rallies. I'm just disappointed to lose. I didn't quite finish the points when I needed to on some short balls and some bad unforced errors in key moments."
Edmund will now head to Cincinnati for the final Masters tournament before the US Open later this month.
He will take positive memories with him, saying: "It was my first Olympics and you've got to enjoy it as much as possible. I'm disappointed I lost but I'll definitely walk away remembering the experience and the good times."
Juan Martin Del Potro was back on court around 16 hours after his emotional win over Novak Djokovic but ensured there was no letdown by defeating Portugal's Joao Sousa 6-3 1-6 6-3.
There was more drama as the match was delayed during the first set because of a fight between spectators in the stands, but the greater concern for Del Potro was his tight schedule.
The former US Open champion, who missed the better part of two years with wrist problems, said: "Last night I went to bed at 4.30 in the morning.
"Today I was having breakfast at nine o'clock. I still can't believe I beat Djokovic and had to play again so soon. And I can't believe I'll have to play doubles (later on Monday). It is very hard, but we'll do what we can."
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