Indian wrestler Narsingh Yadav's Olympic campaign today hit a massive roadblock after the World Anti-Doping Agency (WADA) decided to appeal against the clean chit given to him by NADA in a dope scandal back home.Indian contingent's chef-de-mission Rakesh Gupta informed a news agency that WADA has appealed against the NADA clearance in Court of Arbitration (CAS). He said, now the hearing is on and the IOA Secretary General Rajeev Mehta is there with WADA officials in Rio de Janeiro.Narsingh was supposed to begin his campaign on August 19 but now faces the prospect of a career-ending four-year ban if the Court of Arbitration for Sports (CAS) upholds WADA's appeal.Narsingh had tested positive for a banned anabolic steroid – methandienone – in tests conducted on June 25.The World Championships bronze-medallist had claimed that he was victim of a conspiracy by rivals, a theory that was accepted by NADA which exonerated him after a hurried appeal.He managed to get the NADA and WFI backing in time to board the flight to Rio but could well be grounded for good if WADA's appeal is upheld by CAS.