Two first half headed goals by Gaston Sauro saw Argentina beat Costa Rica 2-0 on Thursday to advance to the quarterfinals of the Under-17 World Cup.
In other matches, Nigeria downed Colombia 2-1, England defeated Syria 3-1, and Germany hung on to beat the United States 2-1.
After a tense opening 25 minutes in Goyang City, Argentina went ahead when Santiago Fernandez' corner was headed in by defender Sauro.
The second goal on 41 minutes was a carbon copy, with Fernandez again finding the head of Sauro.
Costa Rica made attacking substitutes for the second half but could find no way past the Argentine defence.
"This team may not be overflowing with individual talent, but it's packed with typical Argentinian qualities like grit, hard work and intelligence, which is what saw us through," Argentina coach Miguel Tojo said after the match.
Argentina's quest to win its first U-17 World Cup will face a sizeable hurdle in the quarters, where it will meet two-time champion Nigeria.
"Next up are Nigeria, who are very difficult opponents with extremely strong players," Sauro said. "We'll stay faithful to our style, however, and I fully believe that we can win the match."
Nigeria progressed 2-1 over Colombia, rallying with two goals in the last 12 minutes.
Colombia took the lead in the 62nd minute, as Santiago Trellez pounced on a defensive error, rounded the goalkeeper and stroked the ball into the empty net.
Nigeria hit the post soon after and sent on attacking substitutions, and found the equalizer in the 78th minute as substitute Sheriff Isa converted from close range.
Yakubu Alfa scored the winner five minutes later with a curling left-foot shot.
"As for my own team, they have great days ahead of them," Colombia coach Eduardo Lara said. "When you lose the way we did, you can only be confident about the future."
England and its eternal rival Germany will also meet in a quarterfinal after both won Thursday.
England went ahead in the 17th minute when Syria handled a corner, and Henri Lansbury converted the spot kick.
Syria came close to equalizing with a succession of freekicks, but England doubled its advantage in added time at the end of the first half as Krystian Pearce controlled a cross and struck home a low shot.
Syria came back into the game six minutes into the second half via a Ziad Ajouz goal.
The Europeans restored their two goal advantage on 62 minutes when Lansbury crossed for Rhys Murphy to knock home.
The west Asians continued to put on the pressure but poor finishing and some fine goalkeeping by Alex Smithies ensured victory.
Germany was the deserved winner against the U.S. but the Americans came close to dramatically levelling in the dying stages.
Germany took the lead through Richard Sukuta-Pasu on 65 minutes, and the Bayer Leverkusen forward doubled that advantage with just over a minute to play, seemingly securing the match.
However Mykell Bates pulled a goal back for the U.S. in the second minute of added time, and the Americans had two late shots on target but could not score.