Huh Jung-Moo hailed his players' character after South Korea booked their place in the last 16 of the World Cup.
South Korea's 2-2 draw with Nigeria on Tuesday was enough for the nation to secure the runners-up spot in Group B.
Huh's men will now face Uruguay on Saturday in the second round of the tournament.
"The merit goes to the players and to the coaching staff, not to me," said Huh.
"The players and the staff really became one and worked together very hard to get our goal of reaching this stage.
"I am very proud of my players. They were not intimidated and they played to their full potential. I am very pleased."
Of his team's performance against Nigeria, Huh said: "It was a difficult game and I am very happy that we have reached the next stage of the competition.
"During the match we conceded the first goal and we thought that then Nigeria struck the post.
"But our players managed to maintain their cool and equalise.
"When we were leading the game, we allowed the penalty which we should have avoided.
"Those were the critical moments."