Mo Farah should "distance himself" from coach Alberto Salazar, according to former marathon world record holder Steve Jones.
Double Olympic champion Farah is trained by Salazar, who is at the centre of doping allegations.
Salazar denies wrongdoing. There is no suggestion Farah has broken any rules.
"My suggestion to Mo would be to distance myself as soon as I could, regardless of whether there is or isn't something going on," said Jones.
Jones trains runners who compete against Salazar's athletes in the United States.
According to a BBC investigation, Salazar has been accused of violating anti-doping rules, including claims that in 2002 he was involved in doping US record holder Galen Rupp, who also denies any wrongdoing.
Rupp and Farah are part of Salazar's training stable in the United States, but there is no suggestion Farah has broken any rules.
Farah, the Olympic 5,000m and 10,000m champion, told the BBC: "I have not taken any banned substances and Alberto has never suggested that I take a banned substance.
"From my experience, Alberto and the Oregon Project have always strictly followed Wada rules and if there is ever a question seek guidance from Usada to ensure they are correctly interpreting Wada's rules."