Mo Farah is facing being quizzed by anti-doping detectives after they began questioning his Nike Oregon Project team-mates over claims their coach was a drugs cheat.
Farah was in line to be interviewed by the team which brought down Lance Armstrong and has now trained its sights on the man who led Farah to double Olympic gold at London 2012, Alberto Salazar. The United States Anti-Doping Agency (Usada), headed by Armstrong's nemesis Travis Tygart, spoke to Farah's team-mate, Treniere Moser, last week and is expected to approach other members of the camp.
That would include Farah, who on Friday confirmed he would not sack Salazar as his coach in the wake of the explosive allegations against the 56-year-old. It could even include senior figures at UK Athletics, which employs the American as a consultant.
A source close to the 32-year-old 5,000m and 10,000m champion confirmed last night that he would co-operate with any Usada inquiry if approached.
Farah's decision to stand by Salazar could backfire spectacularly both on him and UKA if the claims by several of the coach's former colleagues and athletes lead to Usada charges.
Having already interviewed a dozen whistle-blowers, the agency has stepped up its inquiry, with Moser, a 1,500m runner, confirming yesterday she had spoken to investigators after they approached her.
"I have done my part and I've talked to them and I gave them everything I wanted, that's all I can do," she said. "My whole thing going into it was, as long as I'm truthful, like I have nothing to hide, it's not hard. I told them everything I knew and they were really nice about it. They told me what they were looking for and I just told them what I knew."
Moser said Usada's line of questioning focused on a media interview she gave two weeks ago in which she claimed to have witnessed no evidence of "foul play or wrongdoing" by Salazar or others since she joined the Nike Oregon Project (NOP) shortly after London 2012.
One of the central allegations against the coach is that he abused the system that allows athletes to take banned drugs if they have a medical condition, such as asthma or a thyroid problem. Moser said in her interview that "at this point" she was not on thyroid medication and did not have a therapeutic use exemption (TUE) for the taking of other substances.
Another allegation against Salazar is that he conducted experiments using small amounts of a banned drug to discover how much could be taken and remain undetected by a dope test.
Farah last week denied ever taking performance-enhancing drugs and said earlier this month he had never been on thyroid medication and had only had one TUE in his career. There is no suggestion of any wrongdoing by the 32-year-old 5,000 metres and 10,000m world champion.
Salazar last week released a 12,000-word statement denying being a drugs cheat. He admitted experimenting with performance-enhancing substances but only in order to guard against possible sabotage.