The case of the world No. 1 in men's tennis is at the center of anti-doping protocols and reforms that could redefine its parameters.

Jannik Sinner received a 3-month ban after testing positive for a banned substance, with the Italian initially refusing to accept he would face a suspension.

Sinner asked: "Why would we do that if the first independent tribunal found it was no ban at all, why would I accept three months now?"