Tokyo, July 30 : PV Sindhu, the 2016 Olympics silver medallist and reigning world champion, quelled a superb fightback by Japan's Akane Yamaguchi to win in straight games and reach the semi-finals in women's singles badminton competition at the Olympic Games on Friday. Sindhu seeded sixth here, beat fourth seed Akane 21-13, 22-20 in 56 minutes. Sindhu, after winning the first game comfortably 21-13, was cruising towards victory, having opened up an 11-6 lead in the second game, when Akane started a superb fightback. The Japanese shuttler who had been outplayed by Sindhu in the first game with deceptive and disguised shots, switched tactics to engage the Indian, seeded sixth here, in long rallies, and tire her out. And it looked like Akane would succeed as she fought back from 6-12 down to win 10 of the next 12 points, catching up with Sindhu at 15-15 and taking the lead. Sindhu checked her progress by tapping into her energy reserves as she tightened her game, broke Akane's rhythm with attacking play, and saved two match points to win the game and match at 22-20. From 18-20, Sindhu won the next four points with superb attacking play, keeping Akane on her toes with half-smashes and pin-point drop shots to seal victory in 56 minutes. Sindhu, looking to add a gold medal to the silver she won in Rio, dominated her Japanese rival at the net, created points with her disguised shots, and completed straight games win. The Indian 26-year-old shuttler from Hyderabad was in total control of the first game and then quelled a strong fightback by Akane to reach the semi-finals for the second successive Olympics. Sindhu was really happy with her performance against Akane but was focused on the next match. "I'm happy but it's not over yet. For me, it's time to go back, relax and get ready for the next match. I'm happy but I need to prepare for the next match." Sindhu said the second game was the most important as Akane came back strongly. "There were some very long rallies. The second game was very important, I was leading and Akane came back, so I couldn't relax. On my side, there were a few errors. I wasn't nervous even though she was at game point, my coach was saying: 'It's okay, keep the focus and you'll get there. He was constantly supporting me and that got me by and I'm happy I got back in two games," Sindhu told the BWF. On her ability to rise to the occasion and doing well in the big events, Sindhu said: "I take that as a compliment but I think I have really worked hard for this and it's not over yet and I have to be focused and prepare for the next match. The next one is important." Akane said she tried to be patient against Sindhu but it was difficult to attack. "It was difficult for me to attack her," she said. "I tried to be patient [at game point] but after that, she led by a game. I had a lot of support messages, so I tried to do my best but I lost that game [second game] so that's frustrating. A lot of people supported me and I appreciate that. I worked hard and I'm disappointed. To stand on this stage, it's not a normal tournament, it's very special to me." Akane said the mood in the Japan camp was sombre as compatriot Nozomi Okuhara had lost to China's He Bing Jiao in the first quarterfinal in the morning. "We have had a lot of top-seeded players and everyone expected better of us, but we did our best and I want to go on to the next step in the future," she told the BWF. /IANS