Media playback is unsupported on your device Media caption Archive 2012: Fans jeered as the women's doubles match between China's Yu Yang and Wang Xiaoli and South Koreans Jung Kyung-eun and Kim Ha-na ended in controversy.

The Badminton World Federation has charged eight female Olympic doubles players with "not using one's best efforts to win a match".

Four pairs - two from South Korea, one from China and one from Indonesia - face a disciplinary hearing.

Meanwhile, Team GB's gold medal hopes on day five of the Games lie mainly with rowers Helen Glover and Heather Stanning, and cyclist Bradley Wiggins.

And America's Michael Phelps has won a record 19th Olympic medal.

Spectators booed the two badminton matches played at Wembley Arena on Tuesday, in which the four accused pairs of players appeared keen to lose.

China's Yu Yang and Wang Xiaoli and South Koreans Jung Kyung-eun and Kim Ha-na are among those facing charges.

Both pairs were already through to the quarter-finals. Reports have suggested they both wanted to lose to secure an easier draw.

Meanwhile, in other developments on Wednesday:

GB men's rowing quads sculls made Olympic history by reaching the final

Tour de France winner Bradley Wiggins will be aiming for a medal in the men's individual time trial, as will GB team-mate Chris Froome, the Tour de France runner-up

Team GB's cyclists Emma Pooley and Lizzie Armitstead will compete in the women's individual time trials - after Armitstead's silver medal in the road race was Britain's first medal of the 2012 Olympics

Glover and Stanning will be competing for Britain in the women's pair rowing event. Glover began rowing in 2008 after participating in the Sporting Giants scheme, set up by UK Sport to identify British sporting talent with a view to the London Olympics

The British men's eight rowing team, which includes 40-year-old Greg Searle, will also be contesting their final

GB's Michael Jamieson and Andrew Willis will be taking part in the men's 200m breaststroke

GB gymnast Dan Purvis will be hoping to achieve a podium finish in the individual all-around event

London Rail and Tube services were delayed after signal failures on Wednesday morning, while Transport for London warned that the Jubilee line would be exceptionally busy in the early evening

Roads have closed across Surrey ahead of the Olympic cycling time trials which take place later

Prime Minister David Cameron is to announce the setting-up of a £10m science research centre on the site of the Olympic drug-testing laboratories

Following Tuesday's badminton match, the South Korean players - who eventually won - did not comment, but Yu said she and Wang were saving energy for the knockout stages.

A later match between South Korean third seeds Ha Jung-Eun and Kim Min-Jung and Indonesian pair Meiliana Juahari and Greysia Polii is also under scrutiny by the Badminton World Federation.

A statement from the BWF confirmed that all four pairs would face charges of "not using one's best efforts to win a match" and "conducting oneself in a manner that is clearly abusive or detrimental to the sport".

China's Olympic sports delegation launched an investigation, saying it opposed any behaviour violating "sporting spirit and morality", as reported by state media.

In other key moments on Tuesday, Great Britain's equestrian team won silver in the eventing competition with its team of Tina Cook, William Fox-Pitt, Mary King, Zara Phillips and Nicola Wilson finishing runners-up to Germany.

Team GB women's football side beat Brazil 1-0 at Wembley to set up a quarter final against Canada.

Elsewhere, Michael Phelps won his record 19th medal as part of the gold medal-winning US 4x200m freestyle relay team.

Some 10.2m people switched on to BBC One and digital channel BBC Olympics One to watch him become the most decorated athlete in Olympic history.