British pair Nathan Robertson and Gail Emms will play for at least a bronze medal after reaching the last four of the badminton mixed doubles.
The number four seeds beat China's sixth seeds Qiqiu Chen and Tingting Zhao 15-8 17-15.
The British pair will face Rikke Olsen and Jonas Rasmussen in Wednesday's semi-final, after the Danes shocked top seeds Kim Dong-moon and Ra Kyung-min.
But Tracey Hallam is out of the women's singles after losing to Mia Audina.
After a tight opening, Robertson and Emms produced an excellent run from 8-8 to take the first set.
But the tension started to show after taking a 13-8 lead in the second, Robertson producing a couple of nervous shots as the Chinese went 14-13 up.
"I felt we controlled the match until the very end when we were leading 13-8 and
a bit of tension came in," said Robertson.
"We were in such control but this is the Olympics, and you start thinking about the next round which is the biggest mistake you can make.
"But we are both tough characters and we know what to say to each other to turn things around.
"Gail was strong there at the end for me and it'll be my job when she goes
through the bad patches to do the same."
The pair now have the chance to emulate Simon Archer and Joanne Goode, who took bronze in the same event in Sydney.
Their next opponents, Olsen and Rasmussen, inflicted a first defeat on South Korean favourites Kim Dong-moon and Ra Kyung-min in 14 tournaments, winning 17-14 15-8.
Robertson and Emms have never beaten the Koreans but prevailed against the Danes just six weeks ago at the Malaysian Open.
In the evening session, Emms turned out again - this time with her thigh strapped - in the women's doubles with Donna Kellogg, beating Louisa Wai Chee Koon and Li Wing Mui of Hong Kong 15-4 15-3 to make it into the last 16.
But Robertson was not so fortunate, losing with Anthony Clark in the second round of the men's doubles to Indonesian eighth seeds Eng Hian and Flandy Limpele 15-7 15-12.
The number two seeds Zhang Jun and Gao Ling of China will contest the other semi against Denmark's Jens Eriksen and Mette Schjoldager.
British number one Hallam's hopes of reaching the women's semi-finals ended when she was beaten 11-0 11-9 by Holland's Audina.
The 29-year-old looked out of her depth against the silver medallist from the 1996 Games during the first game.
Hallam managed to fight back in the second, but it wasn't enough as Audina served out for victory.
"I really struggled for length and I wasn't hitting it cleanly at all," Hallam said.
"I would like to have played better, but I really didn't expect to get to
the quarter-finals of the Olympics because I wasn't playing well."
Earlier, Elia Tripp and Joanne Wright moved into the last 16 of the women's doubles with a 17-15 17-14 victory over Bulgaria's Petya Nedelcheva and Neli Boteva.
Tripp and Wright will next face Dutch fifth seeds Lotte Bruil and Mia Audina, a pair they have never previously beaten.
"It was a tight game but we kept the pressure on well enough to pull it out of the bag at the end," said Tripp.
Wright added: "It is good to have a game like that.
"If we had won in 20 minutes then you don't get that much experience in here and we have experience of being under pressure."