Doping

I think the thing with doping in team sports is that you'd probably need the whole team, or at least all of the wide players or midfield/attackers/full backs to be on something to make it really worthwhile.

I don't think a change or unfair advantage in a single player's athletic ability would be anywhere as significant to the outcome of games as a single cyclist's doping could be.

I have been given to understand that cycling, at least in the form of professional stage races, is indeed a team sport.