Olympics: Phelps Triumphs Again as First Major Doping Cases Revealed

Michael Phelps won a 22nd Olympic gold but doping reared its ugly head again Friday as Chinese swimmer Chen Xinyi and Bulgarian athlete Silvia Danekova became the first major cases of the Rio Games.

Chen's failed test after narrowly missing a bronze medal in the women's 100-metre butterfly was announced as athletics headed into the Olympic spotlight needing an antidote to its own doping scandals.

But track and field's dented reputation was hit by the announcement that Danekova had failed a doping test of her own, with Bulgarian television saying she tested positive for the blood booster EPO.

The news came before the first track and field events of the Games on Friday, with three gold medals up for grabs at the Olympic stadium.

In the pool, Phelps was magnificent again in retaining his 200m individual medley title, leaving old rival Ryan Lochte stranded in fifth place. Even second place Kosuke Hagino was nearly two seconds back.

Afterwards, the 31-year-old waved four fingers to show his four gold medals so far in Rio. That has taken him to an incredible 22 Olympic titles and 26 medals overall.

"I say this a lot, but every single day I'm living a dream come true. As a kid I wanted to do something that no one had ever done before and I'm enjoying it," said Phelps.

Simone Manuel of the United States and Penny Oleksiak of Canada shared a dead heat victory in the women's 100m freestyle. Manuel is the first African-American woman to win an individual Olympic swimming gold.

But the spotlight quickly turned to 18-year-old Chen, who won a world championship gold last year in the 4x100 medley team.

The Chinese Swimming Association said Chen tested positive for the diuretic hydrochlorothiazide after Sunday's 100m butterfly final, China's official Xinhua news agency reported.

Chen came fourth just 0.09 seconds behind bronze medalist Dana Vollmer of the United States.

Diuretics can be used to mask other banned substances.

The CSA said Chen, who was due to take part in 50m freestyle heats on Friday, had asked for a second test on the sample to be carried out and a hearing in the case.

The CSA said it has "demanded full cooperation from Chen in the investigation."

"The CSA resolutely opposes use of banned substances," it added.

Later, Bulgarian television reported that Danekova had tested positive for EPO, although the 33-year-old quickly denied wrongdoing.

"I am not guilty, I have done nothing wrong. Four tests were done, three of them were negative. We found out that my fourth test was positive," she said.

- Dibaba targets more gold -

The revelations came after the International Olympic Committee confirmed that a second Kenyan coach had been sent home from the Games for a doping offence.

Media reports named the official as sprint coach John Anzrah, saying he had attempted to impersonate an athlete during a doping test.

With Usain Bolt looming as the biggest draw of the Olympics, three athletics golds will be won on the first day at the Olympic stadium.

Ethiopia's 10,000m star Tirunesh Dibaba, 31, will become the first woman to win three consecutive golds in an individual athletics event if she retains the crown won in London four years ago.

New Zealand's Valerie Adams could also become the first woman to three titles if she can get the shot put title before Dibaba. The women's 20km race walk will also be decided while Jamaica's Shelly-Ann Fraser-Pryce starts the heats as she bids for a hat-trick of 100m sprint victories.

The United States has strengthened its lead in the Olympic medals table with 16 golds overall, five ahead of China.

Simone Biles added the women's all around gymnastics title to victory in the team event on Thursday.

The 19-year-old is chasing five golds in Rio, and few would bet against the 1.45m (4ft 9in) Texan adding to her tally in the apparatus finals to come.

Golf started its return performance at the Rio Games on Thursday.

Australian Marcus Fraser was the early pace-setter with a 63 in the first Olympics round since the 1904 Games in St. Louis. England's Justin Rose marked the occasion with a hole-in-one.

Rugby has also made its return and Fiji's sevens team hammered Britain 43-7, the South Pacific nation's first ever gold medal sparking wild celebrations at home.