Alberto Salazar has been accused of violating anti-doping rules, including claims he was involved in doping US record holder Galen Rupp, in 2002.
Rupp and GB Olympic gold medallist Mo Farah are part of Salazar's US stable, the Nike Oregon Project. There is no suggestion Farah has broken any rules.
Salazar and Rupp deny any wrongdoing.
Salazar is a US athletics legend, who won the New York marathon three years in a row and ran himself unconscious in winning the Boston marathon in 1982.
He is now one of the world's most successful coaches. The head coach at the prestigious Nike running camp based in Portland, Oregon, Salazar has worked with Farah since 2011 and has coached his training partner Rupp for 14 years.
His coaching philosophy involves intensive training and the use of the latest scientific techniques.
