Singapore shuttler Yeo Jia Min claimed the biggest scalp of her fledgling career last night, beating women's world No. 1 Akane Yamaguchi in the round of 32 at the BWF World Championships in Basel.

Yeo, who is unseeded in this tournament, took just 39 minutes to clinch a 21-14, 21-18 victory over the 2018 world championships bronze medallist.

The 20-year-old had a 0-2 head-to-head record against the 22-year-old Japanese before the Basel duel, and last played Yamaguchi at the Badminton Asia Championships in April, when she lost 18-21, 21-8, 17-21.

The world No. 32 attributed her success last night to her ability to stay focused: "I did my best to focus on every point from the start, to be patient but ready for the chance to attack.

"I am happy and more motivated to continue fighting in the next matches."

Yamaguchi had raised her efforts in the second game, even taking a lead at 11-9 but Yeo said she was "more ready to defend and to rally with her" and eventually clawed back the deficit.

Added national singles head coach Mulyo Handoyo: "Jia Min's game today was very consistent, and there was quality in her shots. Her fighting spirit was high when she played against the top seed and tried to control the game by making clear decisions during the tie."

Singapore Badminton Association president Lawrence Leow said: "We are very proud of Jia Min's win. Although it is only round two, it is still very important. It encourages and inspires our players and lets them know that nothing is impossible.

"We are very grateful for the support of Singaporeans, our players will continue to try their very best."

Yeo, the former world junior No. 1, recently won the Hyderabad Open and the Vietnam Open last year. Both were Super 100 tournaments. She will face Vietnam's Vu Thi Trang in the third round.

It was a good day for Singapore in Basel, with Yeo's teammate Loh Kean Yew also producing an upset yesterday.

A week after losing to Sourabh Verma in the final of the Hyderabad Open, Loh gained some measure of revenge by beating the Indian's younger brother Sameer.

The 34th-ranked Singaporean is unseeded at the tournament but prevailed 15-21, 21-15, 21-10 against the 10th seed Sameer.

Loh, 22, said of his 61-minute clash: "It was a long and tough match. We both started well in the first game but he was more consistent throughout the whole first game.

"I managed to pick up the pace in the second game and made sure I took control from the net because the opponent's front skill is good.

"I was determined enough and persevered all the way in the second and third games even when we had long rallies."

This has been a breakout year for Loh, who has reached three BWF World Tour finals. Apart from his loss to 26-year-old Sourabh, he fell to Indonesian Shesar Hiren Rhustavito at last month's Russian Open. Memorably though, Loh beat Chinese great Lin Dan in the Thailand Masters final in January.

The victory against Sameer was a timely one, said Loh.

He said: "The win served as a morale booster for me. I performed better than I expected because I wasn't able to play well during court testing.

"I feel that my form has been quite good recently and I hope to keep it going."

He faces 52nd-ranked Thomas Rouxel in the round of 32 today. Their only encounter was at February's German Open where Loh lost 21-18, 16-21, 14-21 to the Frenchman.

On his prospects against Rouxel, Loh said: "I lost to him the previous time I played with him so I'm going to give my best and try to take revenge."

Continuing on the theme of upsets, five-time world champion Lin suffered a second-round loss to India's H.S. Prannoy yesterday.

Lin, also a two-time Olympic gold medallist, went down to the 30th-ranked Prannoy 21-11, 13-21, 21-7 in 62 minutes.

It was the Chinese player's earliest exit in his 12 appearances at the world championships.

"I don't have enough energy in today's match, especially in the first set," he told Xinhua. "I played better in the second but in the third I just ran out of energy."

Prannoy will take on defending champion and world No.1 Kento Momota of Japan, who beat Spain's Luis Enrique Penalver 21-10, 21-7 to cruise into the third round.