Shin said his team really had a tough match against the Argentines, who were desperately looking to rebound from a 3-0 defeat to England in their opening match.

"I didn't expect to have a really tough match, but Argentina were Argentina today," Shin said at a press conference. "Our players really made sacrifices and did well."

South Korea produced two goals in the first half, thanks to two FC Barcelona prospects Lee Seung-woo and Paik Seung-ho, but conceded their first goal of the tournament when Marcelo Torres' right-footed strike found the back of the net in the 50th. Shin's side had some risky moments until the end of regulation and five minutes of extra time, but was able to secure the victory against the six-time tournament champions.

"I was thrilled, but at the same time, I was also nervous watching the match from the bench," he said. "Argentina tried to sway the match in their favor whenever they had the ball, but today, we showed our strength to defend the lead."

Shin said his players should have earned confidence with the victory.

"I realized that South Korea can play competitive football on the world stage," he said. "I believe that today's victory will take our players to the next level."

South Korea will next face England on Friday in Suwon, Gyeonggi Province, with the group's top position at stake. England played to a 1-1 draw with Guinea earlier Tuesday.

Shin said he is thinking of rotating the squad as South Korea have already joined the last 16, but that doesn't mean they will play loose against England.

"I will look into situations of other groups before rotating the squad," he said. "We still have one match left, and against England, we need to collect at least a draw (to finish first in the group)."

If South Korea beat England, it would be the first time that the national team reached the knockout stage with three victories at the U-20 World Cup. Shin said he has not thought about setting a record.

"We originally thought to pass the group stage with two wins and one draw, and I think we're 80 percent close to our goal," he said. "But I think it's too early for us to celebrate."

Meanwhile, Argentina coach Claudio Ubeda lamented his side's lack of finishing touches. Argentina fired 19 shots, compared to South Korea's seven, and they had 60 percent of ball possession throughout the match.

"Just like the match against England, we had more opportunities than the opponents, but our mistakes made this result," he said. "We have to accept it. We made bad choices to let this happen."

Ubeda, however, said Argentina haven't lost hope of going to the round of 16. Argentina can still become one of the four third-placed team to join. Ubeda's side will meet Guinea on Friday in Seogwipo, Jeju Island.

"We will give out our best efforts in the final match," he said. "I hope we can get an opportunity to reach the round of the 16." (Yonhap)