The 28-year-old South Korean, who represented his country at the Team World Cup in London earlier this year, fell to a seven game defeat 6-11, 9-11, 11-4, 6-11, 11-7, 12-10, 11-8 to 17-year-old Yuta Tanaka from Japan at the Platinum World Tour event in Daejeon. 

Sangeun was the second highest ranked player in action today at the Chungmu Sports Arena, but his experience was not enough to see him beat a teenager ranked 221 places below him.

The loss will not be his only match of the competition, however, as the qualification round is played in a group format.

He will now play China's Zhou Qihao in the final match of their group,

Unlike Sangeun, the Chinese player won his first match, which was also against Tanaka, 11-8, 11-5, 11-8, 5-11, 7-11, 11-8.

"I started well and gained a three-nil head start," said Qihao. 

"In the fourth and fifth games I let my guard down a little and was somewhat flustered; that made me unable to react properly.

"I felt some pressure being my first match; I still need to get used to the environment."

Sangeun's loss was the only surprise result among the top men's names in action.

The highest ranked player in the field today, Japan's Masaki Yoshida, beat Hong Kong's Su Zhi 11-6, 11-3, 9-11, 11-4, 11-10, 13-11, 11-4. 

Following Sangeun's loss, Jang Woojin did bring some success for the host nation.

He beat Slovakia's Thomas Keinath, while another South Korean Cho Seungmin beat Lai Chi-Chien from Chinese Taipei, 6-11, 11-8, 8-11, 11-8, 11-4, 11-2.

The qualification tournament finishes tomorrow.