Ayana insists she's clean after crushing the 10,000m record
Ethiopia's Almaz Ayana was forced to answer doping doubters after obliterating the 23-year-old 10,000m world record to claim the first Olympic athletics gold in Rio.
Ayana produced a startling run at the Olympic Stadium to storm home in 29 minutes 17.45 seconds, taking more than 14 seconds off the highly-questionable mark set by China's Wang Junxia in 1993.
Vivian Cheruiyot ran a Kenyan record to take silver, but was still more than 15 seconds behind her 24-year-old rival. The blue track is clearly quick - the race featured eight national records and 18 personal bests - but Ayana's display was incredible.
Cheruiyot, bronze medallist Tirunesh Dibaba of Ethiopia and Alice Nawowuna, the Kenyan who set the early pace before finishing fourth, all ran times that before this race only Wang had ever bettered.
Earlier this year Chinese state media reported Wang, along with nine team-mates coached by the controversial Ma Junren, had written a letter - penned in 1995 but which had only just come to light - admitting to being an unwilling participant in a state-sponsored doping programme.
Ayana, whose previous PB was 30 minutes 7 seconds, hailed her world record as "a dream come true". Asked for her response to critics doubting whether it was clean, she said: "My doping is my training, my doping is Jesus. Otherwise, nothing. I am crystal clear."
It is understood there was some concern over whether Ayana would even be well enough to race as she appeared ill in the call room.
Jo Pavey finished 15th as she made history by becoming the first British track athlete to appear at five Olympics, the 42-year-old mother of two clocking a season's best 31:33.44.
Pavey, whose team-mates Jess Andrews and Beth Potter finished 16th and 34th respectively, said of Ayana's performance: "When I heard the time afterwards I couldn't believe it. It's so much faster than you could ever imagine someone would run.
"You don't think the Chinese records will ever go. That was an amazing race, I never thought that would happen. I don't know whether to have been pleased or not to have been in that.
"You can't say anything unless you've got any proof, you've just got to admire performances until you know differently. I can't be one to suspect performances unless you've got proof, because it's a sad day if anything's good you've got to suspect it.
"I've got no reason to say everybody who does well is cheating. You just have to hope you can believe what you're seeing."
Pavey, the 2014 European champion, had joked in the run-up to the race that when she heard in 2005 that London had won the bid to host the Olympics in 2012 she thought how sad it was that she would not be able to compete at a home Games.
Four years after London she is still going strong and is targeting next summer's World Championships in the city.
She said: "It does give me motivation to go on to next year, there's a carrot of it being at home again."