Defending champion Andy Murray survived a scare to reach the Olympic men’s singles quarter-finals but Johanna Konta exited the women’s singles.
Murray fought back after losing eight successive games to register a 6-1 2-6 6-3 victory over Italian Fabio Fognini.
But Konta was beaten 6-1 6-2 in just over an hour by number two seed Angelique Kerber of Germany.
And the Wimbledon champion was under pressure going into the third set before winning six games in a row to progress, in the process stretching his winning run to 15 matches following his French Open final defeat by Novak Djokovic in June.
In the mixed doubles he and Heather Watson will face Spaniards Carla Suarez Navarro and David Ferrer, after Romanian pair Monica Niculescu and Florin Mergea withdrew.
A frustrated Konta delivered an error-strewn performance as Kerber registered a straight sets victory.
She and Jamie Murray will face Americans Jack Sock and Bethanie Mattek-Sands in the first round of the mixed doubles at 20:00 BST on Thursday.
Meanwhile, world number five Rafael Nadal maintained his bid to regain the Olympic men’s singles crown he won at Beijing 2008 with a 7-6 (7-5) 6-3 victory over Frenchman Gilles Simon.
The 14-time Grand Slam winner, 30, had not played since the French Open in May because of a wrist injury but is competing in the singles, doubles and mixed doubles in Brazil.
Elsewhere, Argentine Juan Martin del Potro, who knocked out world number one Novak Djokovic in the first round, is into the last eight after a 6-7 (4-7) 6-1 6-2 win over Japan’s Taro Daniel.
“This has been a great tournament, a great week for me already,” Del Potro, the 2009 US Open champion, said.
“I’m looking forward to go far, trying to fight for one medal. I’m still playing well, but the next round is going to be a really difficult match for me.”
Del Potro will play Spain’s Roberto Bautista-Agut next, while Nadal faces Brazilian Thomaz Bellucci.