With top contender Pusarla V Sindhu also falling, to Sun Yu, the group was thrown open. The final group matches tomorrow will decide the semi-finalists.
Japan's Yamaguchi sustained her pacy style even in the late stages of the match to outlast Spain's Marin 18-21 21-17 21-14 in 86 minutes, the longest match of the tournament thus far.
Earlier, Sun Yu got her second big win on successive days, beating crowd favourite Pusarla V Sindhu 21-15 21-17.
After an uneven start, Pusarla had things going her way for a while in the second, working the shuttle around and flicking quick winners. That she couldn't capitalise on a handy 13-9 lead and push the contest into a third game was the story of the match - at important phases the Indian switched to a reactive rather than creative mode, enabling Sun to grab the initiative with her heavy smashes from the back. Once the momentum shifted, the Indian slowly faltered in a clutch of errors, and Sun had the match under control.
In contrast to Group B, the semi-finalists from Group A were decided today, with Tai Tzu Ying joining Sung Ji Hyun into the knockout stage. World No.1 Tai was untroubled by the less-than-fully-fit Ratchanok Intanon (Thailand) as she eased to a 21-12 21-14 result. Intanon, still recovering from a knee injury, was tentative around the court and gave Tai all the openings she needed to quickly finish the job.
'I just commenced training two weeks ago,' said Intanon. 'The first week was about trying to move. I'm getting better. The injury happened before the Olympics, but after that it kept getting worse. I do feel bad missing out on tournaments, especially since so many young players are coming up.'
Li/Liu Crash Out
Malaysia's Goh V Shem and Tan Wee Kiong won a thrilling 58-minute battle against Li Junhui and Liu Yuchen to cement their semi-final place from Group B of Men's Doubles.
Li/Liu second loss meant that they have no hope of progressing to the knockout stage.
Goh and Tan kept their nerve in a tight finish, edging past the Chinese duo 18-21 21-19 21-19. The Malaysians' next match with China's Chai Biao/Hong Wei will decide the group winners.
Meanwhile, in Mixed Doubles, defending champions Chris Adcock/Gabrielle Adcock find themselves in a spot after losing to China's Zheng Siwei/Chen Qingchen 21-17 21-17. The England duo have to win tomorrow's match against China's Lu Kai/Huang Yaqiong, but even that will not guarantee them of a spot in the semi-finals.
Olympic champions Tontowi Ahmad/Liliyana Natsir bowed out of the tournament owing to Natsir's knee injury. The Indonesians retired at 21-8 11-6 down against Denmark's Joachim Fischer Nielsen/Christinna Pedersen. The Danes and another Indonesian pair, Praveen Jordan/Debby Susanto, progressed to the semi-finals.
