In a huge jolt to the Indian wrestling contingent in Rio Olympics, Narsingh Yadav has failed a dope test. His accreditation has also been withheld. Yadav was scheduled to represent the tri-colour in 74 kg category. National Anti-Doping Director General Navin Agarwal confirmed that Narsingh’s ‘B’ sample also tested positive for a banned steroid and he appeared before a NADA disciplinary panel yesterday.