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?"

Jannik Sinner, the world’s No. 1 male tennis player, has accepted a three-month ban from the sport following an anti-doping rule violation. Australian Open champion Sinner, 23, received a sanction in August but was found by the International Tennis Integrity Agency (ITIA) to bear “no fault or negligence” after twice testing positive for clostebol — a banned anabolic steroid — at the Indian Wells Masters 1000 tournament in March.