Novak Djokovic has called for "clear protocols" and "standardised approaches" to tennis doping cases with Jannik Sinner having escaped a ban after testing positive for a banned substance.
The world number one twice tested positive for clostebol - a steroid that can be used to build muscle mass - in March.
The Italian was cleared of fault or negligence by a tribunal last week, with the International Tennis Integrity Agency (ITIA) finding Sinner had been inadvertently contaminated with the substance by physiotherapist Giacomo Naldi.
Naldi had been applying an over-the-counter spray - given to him by fitness trainer Umberto Ferrara - to a cut on his own hand before then carrying out treatments on Sinner.