Shi Yuqi stunned world champion Kento Momota as hosts China whitewashed Japan for an 11th Sudirman Cup title on Sunday.
Japan have never won the badminton world mixed-team championship and their search goes on after they were well beaten 3-0 in the Chinese city of Nanning.
China's dominant victory over the top seeds is an ominous indication of the depth they possess in their ranks with next summer's Tokyo Olympics on the horizon.
Roared on by the home crowd, China went 1-0 up through their men's doubles and then took a 2-0 lead after a captivating women's singles match between Chen Yufei and Akane Yamaguchi.
Japan needed their talisman Momota to beat Shi in the men's singles to keep the tie alive.
The world number one had defeated second-ranked Shi four times in five previous meetings, including last year's world championship final.
It looked like more of the same when the 24-year-old Momota won the first game 21-15, but Shi suddenly found rhythm and his subdued Japanese rival faded spectacularly.
The 23-year-old Shi raced to the second game 21-5 and took that searing momentum into the decider, winning the third game — and with it the Sudirman Cup — 21-11.
Shi sealed the championship with a smash and was mobbed by his team-mates, who raced onto the court after his surprise win.
China, the long-time pre-eminent power in badminton, reclaim the trophy that they lost to South Korea two years ago.