Saudi Arabia 0-2 Senegal
2015 semi-finalists, Senegal began their tournament with a comfortable 2-0 win over Saudi Arabia in the Group F opener.
Ibrahima Niane opened the scoring for the Senegalese in the 13th minute, before Cavin Diagne doubled the lead two minutes later.
The victory sees Senegal move top of Group F, two points ahead of Ecuador and America, and three Saudi Arabia.
Ecuador 3-3 USA
Ecuador and America had to settle for a point in their Group F opener after they played out a 3-3 draw on Monday morning.
Herlin Leno and Bryan Cabezas put the Ecuadorians into a two-goal lead inside the opening 10 minutes. USA hit back through Josh Sargent, who bagged a brace with strikes in the 36th and 54th minute.
Ecuador restored their lead in the 64th minute when Cabezas bagged his second of the game. However, USA left it as Luca de la Torre snatched the equaliser in stoppage time.
France 3-0 Honduras
2013 champions, France began their campaign in style, as they cruised to a 3-0 win over Honduras.
Paris Saint-Germain's Jean-Kevin Augustin opened the scoring after 15 minutes, before Amine Harit and Martin Terrier got the second and third respectively.
Vietnam 0-0 New Zealand
Vietnam claimed their first ever point at an U20 World Cup, after they played out a goalless draw with New Zealand at the Cheonan Sports Complex.