The Argentinians advance as Group F winners due to a superior goal difference over South Korea but, after having it all their own way in their opening two matches, they found themselves outplayed today. 

The breakthrough came three minutes before half-time when Oh Se-hun crashed home an unstoppable header from Lee Kang-in’s left-footed cross.

Twelve minutes after the restart, Cho Young-wook swept South Korea’s second into the roof of the net following a fine run on the left by Jeong Ho-jin.

Cristian Ferreira did pull a goal back two minutes from time with a speculative long-range shot that deceived keeper Lee Gwang-yeon, but it was to prove too little, too late for Argentina.

The other match in Group F saw South Africa earn a 1-1 draw against Portugal at Bielsko-Biala Stadium, ensuring the European champions missed out on the round of 16.

Centre-forward Rafael Leão opened the scoring in the 19th minute after settling Thierry Correia's cross from the right side and poked past goalkeeper Khulekani Kubheka from close range.

South Africa won a penalty in the 52nd minute after the Video Assistant Referee judged Diogo Leite had handled, before Thabiso James Monyane converted calmly from the spot.

Just five minutes later, Portugal were awarded a penalty of their own in a near-identical situation with South Africa's Fezile Gcaba the handball culprit. 

But Kubheka saved well from Jota's resultant effort as the Portuguese were sent packing.

In Group E, France claimed a 3-2 victory over Mali at Gdynia Stadium to make it three wins out of three. 

Mickaël Cuisance opened the scoring for French in the 12th minute, firing past Youssouf Koita from range, but Mali's Sékou Koïta responded with a left-footed strike of his own.

The second-half was evenly balanced until a handball by Abdoulay Diaby earned France a penalty, which Moussa Diaby converted.

Amine Gouiri made it 3-1 with a well-placed shot in the 87th minute, before fellow substitute Ousmane Diakité got Mali's second with virtually the last kick of the game.

Panama beat Saudi Arabia 2-1 in the other Group E match at Bydgoszcz Stadium to secure the first FIFA Under-20 World Cup finals victory in the country's history.

Axel McKenzie opened the scoring for Panama with a well-worked goal down the left flank in the seventh minute.

Shortly after the break, forward Feras Albrikan scored a superb equaliser for Saudi Arabia but Panama came again 12 minutes from time with Diego Valanta tapping home.

Panama were one of the four best third-placed finishers alongside hosts Poland, Nigeria and Ecuador. 

They all qualified for the knockout stage, while Portugal and Norway missed out.

Following a rest day tomorrow, the first two round-of-16 ties are scheduled for Sunday (June 2).

Italy face Poland before Colombia meet New Zealand.