Rio de Janeiro, Aug 17 Star shuttler P.V. Sindhu stunned World no.2 Wang Yihan of China to provide the bright spot in another dismal day for India at the Rio Olympics even as the World Anti-Doping Agency\'s (WADA) appeal in the Court of Arbitration for Sports (CAS) against the clean chit to wrestler Narsingh Yadav dampened the country\'s medal chances further.

Sindhu caused a huge upset, stunning World No.2 Wang Yihan of China in straight games to enter the semi-finals of the women\'s singles category at the Riocentro Pavilion 4 here on Tuesday.

Faced with a much higher rated opponent, the 21-year-old from Hyderabad scripted a 22-20, 21-19 victory in 54 minutes over the former World No.1.

Sindhu will face World no.6 Nozomi Okuhara of Japan in the last-four stage. Okuhara defeated compatriot Akane Yamaguchi 11-21, 21-17, 21-10 in a hard-fought all-Japan quarter-final clash which dragged on for one hour and eight minutes.

Wang, who had taken silver at the 2012 London Olympics, was expected to be the stronger of the two in Tuesday\'s encounter, but it was Sindhu who dominated most of the exchanges.

The World no.10 Indian won the majority of the long rallies and used her power-packed smashes and cross-court shots to good effect.

Wang, whose weak back-hand caught her off-guard several times, came up with a tough fight, but could not do enough to stop Sindhu.

Talking after Tuesday\'s quarter-final, Sindhu asserted that she is determined to produce a similar effort in the semi-finals and create history by becoming the first Indian shuttler -- male or female -- to enter the Olympic final.

\"Yes, this is one of the most satisfying wins that I have played. I have played Wang Yihan several times and sometimes she plays a different game. This one was one of the best, and I hope it will happen in the next game,\" she said.

\"In the first game, she shot very well. My win was not really luck, since she played brilliantly. I was down in that game, but then I came back. Even though she was leading, I knew the game could change any moment. After that the score was going equal and it was not easy to get a point for either of us,\" she added.

But away from the badminton court, the by now familiar sense of gloom continued to haunt the Indian camp. If the failure to open their account in the Olympics medals tally wasn\'t enough, WADA piled on the misery for Indian fans by appealing to the CAS against the clean chit to Narsingh.

Narsingh, who was exonerated of doping charges on August 1 by the National Anti Doping Agency (NADA) terming him \"a victim of sabotage done by a competitor\", is scheduled to open his Olympic campaign in the men\'s 74 kilogram freestyle category on Friday, a day after the hearing is scheduled to take place.

\"Yes, WADA has appealed the verdict on Narsingh to CAS, which will hear both parties on Thursday August 18,\" Wrestling Federation of India (WFI) President Brij Bhushan Sharan Singh told IANS.

\"Our lawyer has already acknowledged the WADA letter. We will put up a strong defence for Narsingh. He has a good chance of getting cleared,\" he added.

But WADA\'s appeal just two days before the bout may seriously affect his chances, considering the whole drama that unfolded starting with the legal tussle with two-time Olympic medallist Sushil Kumar over representing the country in the 74kg freestyle category followed by the doping saga.

The Mumbai grappler was preferred over Sushil by the WFI to take part in the Games, that fuelled a major legal battle between the two wrestlers.

Narsingh, who bagged the quota with a bronze medal finish in last year\'s World Championships, first returned positive for a banned steroid following a dope test on June 25 by NADA, before being cleared on August 1.

The WFI also communicated to the world\'s apex wrestling body, the United World Wrestling (UWW) that NADA has cleared Narsingh of all the doping-related charges and the 26-year-old would be re-included in the team for the men\'s 74kg freestyle competition.

The UWW gave the green light to Narsingh for Olympic participation on August 3. However, Narsingh\'s route had to clear the final WADA hurdle to compete, which reviewed the NADA panel verdict and challenged it at CAS for further deliberation.

To add to the disappointment, during the day wrestler Hardeep Singh crashed out of the men\'s Greco-Roman 98 kg 1/8 Final after losing to Turkey\'s Cenk Ildem 1-2 on points.

Hardeep\'s elimination has brought down the curtains on India\'s campaign in the Greco-Roman category after Ravinder Khatri lost to Hungary\'s Viktor Lorincz by technical superiority in 85kg on Monday.

India will now pin their hopes on the freestyle wrestlers led by London Olympics bronze medallist Yogeshwar Dutt in the 60 kg category, Narsingh (subject to his clearance) and Sandeep Tomar in the 57kg category.

Besides them, the women\'s field comprising Vinesh Phogat in 48kg, Babita Kumari in 53kg and Sakshi Malik in 58kg categories will also aim for a podium finish in their respective categories.

Sindhu only bright spot as WADA keeps Narsingh hanging