Oh Se-hun and Cho Young-wook scored a goal apiece in Group F finale at Tychy Stadium in Tychy, Poland, as South Korea reached the round of 16 for the second straight tournament. Cristian Ferreira had the lone goal for Argentina.
South Korea finished in second place in the group, behind Argentina, with six points from two wins and a loss. Argentina also had six points but were ahead of South Korea in goal difference, plus-4 to plus-1.
South Korea needed at least a draw against Argentina to punch their ticket to the round of 16, but they clinched the knockout berth in style by upsetting the South Americans, who'd scored seven goals in two previous matches.
The top two teams from each of the six groups, plus four best third-place teams, qualified for the round of 16.
In the round of 16, South Korea will face Japan, Group B runners-up, in Lublin next Tuesday.
South Korea's best showing at the youth tournament was a fourth-place finish in 1983 in Mexico. As the hosts of the previous competition in 2017, South Korea fell to Portugal 3-1 in the round of 16.
