Eight women badminton players were charged by the sport's governing body on Wednesday with "not using one's best efforts to win a match" after two matches at the Olympics ended in controversy.
Four pairs in the women's doubles competition - one from China, one from Indonesia and two from South Korea - could face disciplinary action after the Badminton World Federation (BWF) took action.
The players in two matches were booed off court at Wembley Arena in London on Tuesday after they appeared to deliberately serve into the net, or hit the shuttlecock long or wide.
It was apparently an attempt to manipulate the final standings in the first-round group stage with two pairs who had already qualified from the group stage jockeying to play against weaker opponents.
The 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 after the Chinese lost heavily.
There were no rallies of more than four shots in the match.
Their defeat meant Yu and Wang avoided playing their compatriots Tian Qing and Zhao Yunlei, who had finished second in their group.
Yu said afterwards: "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."
A later match in which South Korean third seeds Ha Je and Kim Min-Jung beat Indonesian pair Meiliana Juahari and Polii Greysia is also being investigated by the BWF.
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players about their conduct and was thought to have shown a black card -- meaning a dismissal --but it was apparently rescinded.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 after the match: "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."