Anti-doping authorities must take action against world number one Jannik Sinner after he escaped a ban by a tennis agency despite two positive tests for a banned steroid, German anti doping expert Fritz Sörgel has said. “It stinks to high heaven,” Sörgel told broadcasters Sport1 on Wednesday. What happened? The International Tennis Integrity Agency (ITIA) said on Tuesday that the Italian tested positive twice for low levels of clostebol in March, a few weeks after his first grand slam title at the Australian Open. The ITIA absolved Sinner of fault and negligence as it accepted his explanation …