The International Olympic Committee wants team coaches, trainers, or officials of the four doubles pairs to be punished if they encouraged or ordered the eight, now-disqualified players to lose intentionally.

The doubles teams — the top-seeded pair from China, two pairs from South Korea, and one from Indonesia — were also set to have their accreditations removed by their national Olympic bodies and sent home.

Defending Olympic champion Yu Yang of China went further by apparently announcing her retirement from badminton.

‘‘This is my last game,’’ read a posting on a verified account for Yu on the Tencent micro­blogging service. ‘‘Farewell Badminton World Federation. Farewell my dear badminton.’’

Yu’s retirement could not be immediately confirmed with Chinese badminton officials and was not referenced in an interview with state television.

‘‘I think firstly we should apologize to the Chinese audience, because we did not demonstrate the Olympic spirit . . . We did not give the audience a game that fully demonstrated our skills,’’ Yu said. ‘‘And it really resulted in a lot of negative influence.’’

Chinese badminton coach Li Yongbo also issued an apology, saying: ‘‘It’s me to blame.’’

‘‘We didn’t take each competition seriously and follow the Olympic spirit of ‘higher, faster and stronger’ as professional athletes,’’ Li added on Chinese television.

Yu and Wang Xiaoli, the world champions and Olympic gold medal favorites, were one of four doubles teams that played poorly on purpose to secure a more favorable position in the quarterfinals lineup. The Chinese pair drew jeers as they intentionally lost to the South Koreans to rig the draw so they wouldn’t have to face their second-seeded compatriots in the semifinals.

‘‘We did not fully understand the significance of it,’’ Li said.

Indonesia’s badminton federation on Thursday called for future Olympics to scrap the group-stage format which can allow results to be manipulated and return to a straight knockout tournament.

Opportunity knocks

The group stage in women’s soccer is done. On Friday, eight teams, all considered medal contenders, enter the knockout stage.

The US takes on New Zealand in Newcastle, and coach Pia Sundhage wants her team to keep attacking. The Americans swept their three games in group play for the first time in Olympic competition, so the quarterfinals is not the time to start playing conservatively.

‘‘This is when we knock them out,’’ said Sundhage, pounding her first into her palm. ‘‘Still finding the rhythm and keep your playing style, and don’t let too much up.’’

New Zealand coach Tony Readings said it would be a ‘‘massive feat” for his team to beat the top-ranked team in the world. The US-New Zealand winner will play the Britain-Canada winner in the semifinals.

Sweden vs. France and Brazil vs. Japan make up Friday’s other quarterfinals.

First swimmer to six

Lars Frolander, 38, of Sweden failed to advance from the 100-meter butterfly heats on Thursday, but he still became the first swimmer to compete in six Olympics.

“I'm really happy and pleased with my career even though I'm not pleased at all with my race this morning,’’ said Frolander, who finished 20th in the heats.

Frolander’s Olympic career began 20 years ago in Barcelona, when he won a silver medal in the 4 x 200-meter freestyle relay. Sweden also finished second in the event in 1996 in Atlanta, and Frolander won his only individual medal in Sydney in 2000, a gold in the 100-meter butterfly.

On Thursday, he didn’t sound like someone preparing to compete in Rio de Janeiro in 2016. ‘‘This is it,’’ Frolander said. ‘‘You should never say never, but I don’t think so.’’

Merritt on mend

With the men’s 400-meter race on Saturday, how healthy is defending champion LaShawn Merritt after he tweaked his left hamstring two weeks ago?

‘‘It’s difficult to tell’’ if Merritt will be completely healthy, his coach, Loren Seagrave, wrote in an e-mail to the AP Thursday. Seagrave said Merritt has been resting and rehabbing the hamstring and is ‘‘much improved and pain free.’’

Merritt, who returned to track last season after serving a 21-month drug suspension, is a heavy favorite in the event.

‘‘He’s been focus(ed) on treatment, rehab and training, so there’s been little chance to dwell on any implications of being the defending Olympic champion,’’ Seagrave wrote.

Special delivery

Some of England’s iconic red mailboxes have been painted gold to celebrate the medals won by British Olympians. It’s the first time the mail service has changed the color of its mailboxes in more than a century. The boxes have been red since 1874 . . . China’s men’s basketball team may be without star forward Yi Jianlian, who appeared to twist his right knee late in a loss to Australia on Thursday. Chinese coach Bob Donewald said it was too soon to determine the severity of the injury . . . Suspended French runner Nordine Gezzar lost his late legal bid to compete on Friday in the men’s 3,000-meter steeplechase. The Court of Arbitration for Sport said its special Olympic court rejected his urgent appeal against exclusion by the French team for doping.