South Korean swimmer Kim Woo-min set a new national record in men's 800-meter freestyle at the World Aquatics Championships in Japan on Tuesday.

The 21-year-old finished first in his heat at Fukuoka's Marine Messe Fukuoka Hall with a time of seven minutes 47-point-69 seconds to best the previous record held by Olympic champion Park Tae-hwan of seven minutes 49-point-93 seconds.

The record stood for over ten years since Park set it as he reached the 800-meter mark in the one-thousand-500-meter freestyle event at the 2012 London Olympics.

Despite the new record, however, Kim came short of advancing to the final, finishing 14th out of 38 swimmers, with only the top eight moving on to the final round on Wednesday.

He still managed to show his potential on the international stage, also finishing a career-best fifth in the 400-meter freestyle, with a personal best of three minutes 43-point-92 seconds.