Top seeds Son Wan-ho and Tai Tzu-ying crashed out of their respective men's and women's singles draws at the semi-final stage of the Badminton World Federation Denmark Open in Odense.
South Korea's son was beaten by compatriot Lee Hyun-Il in a three-set epic at the Odense Sports Park.
Lee, 37, rolled back the years to end a run of four straight losses against an opponent eight years his junior.
A marathon first set proved key as he eventually triumphed 25-23, 18-21, 21-17.
Kidambi Srikanth of India lies in wait in the final after reaching the last stage at a fourth World Superseries event this year.
He won 21-18, 21-17 over Hong Kong's Wong Wing-ki.
Thailand's 2013 world champion Ratchanok Intanon continued her good form in the women's draw with a first victory over Taiwan's Tai after three straight losses.
She survived a narrow reverse in the second set to win 21-14, 20-22, 21-14.
Japan's Akane Yamaguchi is one match away from successfully defending the title she won last year.
She was also stretched to three sets before defeating Chen Yufei of China, 10-21, 21-18, 21-19.
All finals will take place tomorrow.