Rio de Janeiro: Star shuttler P.V. Sindhu entered the women's singles final to assure India of a second medal at the Rio Olympics while the Indian contingent suffered a blow with wrestler Narsingh Yadav being banned for four years over a doping offence. Sindhu assured the country of at least a silver medal after thrashing Japan's Nozomi Okuhara in straight games in the women's singles badminton semi-final at the Rio Olympics here on Thursday. World No. 10 Sindhu continued with her giant-killing spree as she made light work of the Japanese to register a 21-19, 21-10 triumph in the semi-finals and become the first Indian shuttler to enter the final of the Olympics. However, the euphoria in the Indian camp turned into dismay later in the day when Narsingh's dream of competing at the Rio Olympics came to an end with the Court of Arbitration for Sport (CAS) upholding the World Anti Doping Agency's (WADA) appeal against the clean chit given to him by the National Anti Doping Agency (NADA) in a doping violation case.