Portugal and Nigeria won their final Group B matches to reach the last 16 of the Under-20 World Cup on Thursday, while third-place South Korea still has a chance of advancing.

Portugal striker Bruma scored his fourth and fifth goals of the event to help the two-time champions beat Cuba 5-0 and top the group, while Nigeria defeated South Korea 1-0 after an early goal by Olarenwaju Kayode and overtook the Asians for second place.

Ricardo, Aladje and To Ze also found the net for Portugal, while Bruma almost added a sixth but hit the crossbar.

It was Portugal's biggest ever win in the competition, improving on 3-0 defeats of Argentina in 1991 and the Netherlands four years later.

Portugal won the title in 1989 and `91 and finished runner-up to Brazil two years ago. Cuba, which lost all three games and became the first team to be eliminated, was making its debut appearance.

Nigeria secured its victory after Kayode was left unmarked by the South Korean defense and headed home a free kick by captain Abdul Ajagun in the ninth minute.

South Korea still has a chance to advance as one of the best four third-place teams.

Spain and France had already advanced from Group A, and Spain won the group with a 2-1 win over the French.

Ghana rendered the United States last in the group with a 4-1 defeat of the Americans, who haven't passed the group stage since 2007. (AP)