Argentina defeated Guatemala 3-0 on Tuesday to guarantee its place in the Under-20 World Cup's knockout round.
With a 3-0 win against Fiji in Group B, the US advanced to the Round of 16.
Argentina easily defeated Guatemala, with Alejo Veliz's header in the 17th minute giving the tournament hosts the lead. The Santiago del Estero locals had it easy when midfielder Carlos Santos received a red card in the 58th minute, and Luka Romero increased their advantage in the 65th.
Tomás Aviles of Argentina was dismissed in the 82nd minute, but the home team still had a chance to score in dead time when Máximo Perrone pushed the ball into an open goal.
Sherzod Esanov scored in extra time in the previous Group A game as Uzbekistan fought to hold New Zealand to a 2-2 draw. Benjamin Wallace and Jay Herdman both scored goals in the first half to put Uzbekistan down 2-0. The comeback was launched with a goal by Abbosbek Fayzullaev in the 51st minute.
With six points after two games, Argentina cannot position worse than second in the group. The six-time winners take face New Zealand on Friday. Uzbekistan, which closes the group stage against Guatemala, has one point while New Zealand has four.
At the 24-team competition, the top two teams from each group and the four best third-place teams will proceed to the Round of 16.
The Americans didn't score until midfielder Diego Luna curled in a shot from the outside of the box in the 66th minute earlier, as Fiji sat back in defense. After winger Cade Cowell doubled the advantage with a similar goal in the 88th minute, defender Caleb Wiley completed the scoring with a tap-in in stoppage time.
After two wins in Group B, the United States has six points, while Ecuador and Slovakia each have three points and might possibly get there.
The Ecuadorians, who had one of the tournament's talents in scorer Kendry Paez, defeated Slovakia 2-1 in San Juan. Máté Szolgai, a midfielder for the Slovaks, scored in the 29th minute, but Ecuador answered with goals in the 59th and the half from striker José Klinger and center forward Justin Cuero.
In the last match of the group stage, the U.S. will play Slovakia while Ecuador will play Fiji.