Goals from Lee Seungwoo, Lim Minhyeaok and Paik Seungho downed Guinea 3-0 in the 2017 U-20 FIFA World Cup Group A match staged at Jeonju World Cup Stadium on Saturday.
The win takes the hosts to the second spot with three points and three goals, equal with England as leaders in the group.
Coach Mandjou Diallo took the matters to their hosts as they managed to absorb the pressure and had some good touches going forward.
However, it was Momo Yansane who took a brilliant shot in the 12th minute when he managed to evade his marker, yet he failed to hit the target as it went over the crossbar.
Goalkeeper Moussa Camara was called to action in the 23rd minute when Korea whipped in a dangerous set piece, the 18-year-old keeper punched the danger away.
Towards the 30th minute, consecutive errors by Camara nearly allowed the hosts to score when Lee Sangheon's header went wide as he tried to catch the keeper out of his line.
With nine minutes to go to the interval, Barceloná's Lee Seungwoo broke the deadlock as he unleashed a fine strike from the d-line to beat Camara on his right corner, 1-0 to Korea Republic.
On the stroke of half time, the hosts doubled their lead through Lee Youngwook, who finished from close range, but it was later disallowed by the video review panel of referees.
It was 1-0 at half time.
The opposite half failed to create some sparks in the opening stages with the hosts playing from the back to invite the West Africans.
Following good passing in the midfield, Guinea were awarded a set piece and they quickly took it, allowing Yansane to see his well struck attempt saved by Song Bumkeun.
Lim Minhyeaok made it 2-0 for the hosts in the 76th minute when he showed great composure after receiving a wonderful through pass from Seungwoo – the substitute beat Camara with a low shot.
Things became more harder for the Africans as Paik Seungho made it 3-0 with a cool finish from close range after receiving a brilliant header crossing from the left wing.
In the last two minutes, Mamadou Kane showed some great skill in the middle of the field, beating his marker, yet he failed to beat keeper Bumkeun, who swallowed the shot.
However, the loss condemns the Young Menas to the bottom of the log table with zero points from one game, and they will now hope to beat England on Tuesday.