British athlete Laura Muir 'doubts' whether the 1500m final she participated in at the Rio Olympics can be trusted.
The same event four years ago at the London Games was later dubbed 'the dirtiest race in history', with six of the top nine finishers testing positive for performance-enhancing drugs at some point.
Muir had been considered a medal prospect in the 2016 version - particularly after an excellent semi-final display.
She came seventh instead, paying for her bold decision to join a breakaway as she tired in the latter stages.
Asked if she believed the race had been a completely clean one, the Scot said: "I have my doubts, let me say that."
The 23-year-old Glaswegian also suggested her final position in the race might improve in the future.
Silver medallist Genzebe Dibaba's coach Jama Aden was arrested in June by police following an IAAF and Spanish authorities anti-doping raid at a hotel near Barcelona.
During the operation, a range of banned substances including EPO were discovered and he remains under arrest so has not travelled to South America.
Ethiopian world record holder Dibaba maintains she is clean and has stressed the impact of conjecture surrounding Aden has affected her performance and mental wellbeing.
Great Britain's Laura Weightman ran both in 2012 and this year, finishing 11th in Brazil, and also has reservations about the legitimacy of the entire field.
"I'm delighted for the medallists there, Faith Kipyegon and Jenny Simpson," she said, before choosing not to reply when it was highlighted she had not mentioned Dibaba.
Weightman added: "This final was much better than in London, but at the time of London I was only 21.
"I didn't really know what was going on. My eyes have been opened a lot more in the last few years. We have made huge steps forward."
Dibaba faced pressure from reporters in the aftermath of the race in the early hours of Wednesday morning for retaining Aden as her coach thus far.
She said: "The world knows my coach is purely for my training. I had blood and urine [samples taken] four, six, eight times this year. I assure you I am crystal clean.
"He is under IAAF custody. The evaluation is undergoing. If he is clean, I will stay with Jama. If it is worse, I will stop."