Yu (left) said after the match: "We've already qualified, so why would we waste energy?" The Olympic Games was rocked by scandal on Wednesday after eight women badminton players were charged with "throwing" matches. Four pairs in the women's doubles competition -- one from China, one from Indonesia and two from South Korea -- could be disciplined after the Badminton World Federation (BWF) took action.
There were also calls for the players to be disqualified and for opponents who finished in third place in the round-robin groups to be awarded quarter-final places instead.
The controversy overshadowed a day when 20 golds are to be decided and could even threaten the sport's future in the Games.
At present, all four pairs are included in the order of play with their quarter-finals scheduled for Wednesday evening, starting from 1600 GMT at the Wembley Arena.
Angry spectators jeered and booed the players after they appeared to deliberately serve into the net or hit the shuttlecock long or wide.
They were allegedly attempting to manipulate the final standings in the first-round group stage, with two pairs who had already qualified apparently wanting to lose to secure a favourable draw in the next round.
The Group A match between the powerful Chinese pairing of Yu Yang and Wang Xiaoli and unseeded South Korean pair Jung Kyung and Kim Ha Na came under scrutiny by the BWF after the Chinese lost heavily.
The longest rally in the match was just four shots.
Their defeat meant Yu and Wang avoided playing fellow Chinese pair Tian Qing and Zhao Yunlei, who had finished second in Group D.
 Yu said after the match: "We've already qualified, so why would we waste energy? It's not necessary to go out hard again when the knockout rounds are tomorrow."
After the match, South Korean head coach Sung Han-Kook reportedly said: "It's not the Olympic spirit to play like this. How could the number one pair in the world play like this?"
Another South Korean coach, Kim Moon-Soo, told the Xinhua news agency: "I think the Chinese players violated the Olympic spirit when they deliberately missed their serves."
China's Olympic delegation has launched an investigation into the allegations, state media said.
"The Chinese Olympic Committee... opposes any kind of behaviour to violate the sporting spirit and morality," Xinhua news agency quoted a Chinese Olympic spokesman as saying.
A later Group C match played Tuesday in which South Korean third seeds Ha Jung-Eun and Kim Min-Jung beat Indonesian pair Meiliana Jauhari and Greysia Polii is also being investigated.
Tournament referee Torsten Berg came on to court during that match to warn the players about their conduct and was thought to have shown a black card -- meaning a dismissal -- but it was apparently rescinded.
Berg said afterwards: "We have looked seriously into the case and as referee I have taken a decision and made a report to the BWF which will be known in due course."
Elsewhere, 20 golds were due to be decided on the busiest day of action so far.
Tour de France winner Bradley Wiggins bids to become Britain's most successful Olympian when he goes in the time trial race, while Australia's James Magnussen looks for a first swimming gold.
Wiggins starts as favourite for the 44km time trial around London's Hampton Court Palace after winning both long time trials on the Tour.
The first Briton ever to win cycling's most prestigious race said he was determined to win Olympic gold after the host nation finished outside the medals in the road race on Saturday.
"Confidence is sky-high that we're going to be in the ballpark," said the 32-year-old Londoner.
 A medal of any colour would see Wiggins become the most decorated British Olympian in history as a seventh medal would put him one clear of rower Steve Redgrave, who has six.
Magnussen came to London with a growing reputation but admitted he got the reality check he needed after Australia's humiliating flop in the 4x100m freestyle relay, and said he was back on track for Wednesday's 100m freestyle.
The 21-year-old world champion nicknamed "The Missile" admitted he was on a steep learning curve at his first Games.
"Everyone says it and I hear it so often, that the Olympics is a different pressure and I used to think 'yeah'... but it's true," he admitted.