Heading into the title clash at the Mangupura Hall, two-time Olympic medallist PV Sindhu was looking to win her second BWF World Tour Finals title and clinch her first top podium finish since winning the 2019 world championships in Basel.
An Seyoung, however, presented a formidable challenge for the Indian.
The 19-year-old in-form South Korean had won the Indonesia Masters and Indonesia Open at the same venue. And came into the match with a 2-0 head-to-head record against Sindhu. She had beaten the Indian in straight games on both occasions.
An Seyoung controlled the opening exchanges of the first game against the reigning world badminton champion Sindhu and raced to a formidable 11-5 lead before the midway break.
The South Korean continued inflicting damage with her lethal cross court smashes after the restart and cruised to a 21-16.
In a must-win scenario, PV Sindhu took a much more aggressive approach in the second game but An Seyoung's superior court coverage and clever shuttle placement didn't allow the Indian shuttler any meaningful inroads. The South Korean held a three-point advantage at the break.
The gap only widened after play resumed as An Seyoung wrapped up the match in 39 minutes to claim her maiden BWF World Tour Finals title.
PV Sindhu will be next seen defending her world championships title at Huelva, Spain, next week.