Kim So-hui, the 2016 Olympic gold medalist in the 49kg, had earlier won world titles in 2011 and 2013 in the under-46kg division.

The top-seeded South Korean got off to a shaky start to her day. In the round of 32, Kim needed an extra period to defeat Courtney Eardley of Britain 4-2. In the round of 16, Kim held off Charlotte Craig of the United States 18-13.

In the quarterfinals, Wenren Yuntao, the 25th-seeded fighter from China, gave Kim all she could handle. The South Korean was nursing a 6-4 lead in the third round, but then took back-to-back "gam-jeom," or deduction penalties, to let Wenren tie the score at 6-6.

Then just five seconds into the sudden-death extra round, Wenren got her two "golden points" to beat Kim 8-6. If the score is tied after three two-minute rounds, the first athlete to score a point in the extra period is declared the winner.

Kim Hun, seeded fourth, beat Hayder Shkara of Australia 24-15 in the round of 64, and then edged out Achraf Mahboubi of Morocco 8-7 in the next match.

Kim then took down Raihau Chin of France 22-15 to reach the final eight. In the quarterfinals, though, Kim proved to be no match for Maksim Khramtcov of Russia, who manhandled him in a 27-5 victory.

Their match was called with 34 seconds left the third round on the "point gap" rule. If one athlete is up by 20 or more points through the first two rounds or at any point during the third round, that athlete is immediately declared the winner.

This was Day 2 of the biennial competition, which will wrap up on Friday. (Yonhap)