Tennis fans were shocked to see a more muscular Jannik Sinner return to action after serving his three-month ban.

The men's world No. 1 missed several tournaments, but no Grand Slams. Here's what to know about the doping proceedings against him.

Jannik Sinner's doping case has generated an incessant debate among players and insiders in recent months. The world number 1 was supposed to be judged by the CAS in Lausanne in mid-April – after WADA had requested a ban of one to two years – but the parties came to an agreement at the beginning of February and the Italian ace was suspended for only three months (from February 9 to May 4).