A stunning win by the US on Friday has put four-time champion Brazil on the brink of a possible shock elimination from the Under-20 World Cup.
The 2-1 defeat left Brazil third after the completion of group D, and reliant upon other results to sneak into the second round as one of the four best-performed third-placed teams among the six groups.
The US victory meant they finished top of the group and thereby get to play one of those third-placed wildcards in the second round.
Aside from 1979, when they did not take part, Brazil have been among the final eight at every U-20 World Cup.
With North Korea having finished third in group E with an inferior record to Brazil, the South Americans still have a reasonable hope of being one of those third-placed wildcards, with everything hinging on the final games in other groups.
Brazil's arch rival Argentina did progress to the second round on Friday, along with Poland and the Czech Republic.
Jozy Altidore scored both goals for the US, with the winner coming in the 81st minute.
He put his side ahead in the 12th minute, but Brazil equalized through Leandro Lima in the 64th.
The Americans spent much of the second half camped in their own half, but in a rare break forward, Freddy Adu dribbled in from the right and his shot rebounded off a defender to Altidore, who was on hand to knock the ball into an empty net.
In the other group D match, Dawid Janczyk scored just before half-time as Poland drew 1-1 with South Korea to take second place and a berth in the second round.
Poland will meet Argentina in the second round on Thursday.
Lee Sang-ho scored the equalizer in the 71st minute for South Korea.
Goalie Bartosz Bialkowski was the Polish hero, pulling off a fine save in injury time to preserve the point which kept them above Brazil.
In group E, defending champions Argentina finished atop the group thanks to a 1-0 victory over a determined North Korea.
North Korea finished third in the group, but their record means they can not be one of the third-place wildcards.
In the other group E match the Czech Republic beat Panama 2-1 to reach the second round.