Sport can never be completely free of doping, according to US track legend Michael Johnson.
"I think it's unrealistic to expect any sport to be completely free of doping," Johnson told the Gulf Times newspaper here where he played the Pro-Am preceding the European Tour Qatar Masters.
A dope-free world of sport was "like expecting a society completely free of crime", said the multiple world and Olympic 400 and 200m gold medallist who still holds world records over the two distances.
"There is obviously going to be some people who will try to take short cuts and cheat.
"There are good people and bad people in society and that will always be there. You have to understand that sports is just a microcosm of the society."
Johnson said the United States would still be the leading track and field nation at this year's Olympic Games despite its recent problems with doping.
"It's going to be a bit difficult for them (China) to make it to the top at this point of time. China is a strong sporting country but America is stronger.
"I think this Olympics would be one of the first times that people will watch the medals table a little bit more closely," said Johnson who had won 54 straight 400m finals.