South Korea's World Cup hopes are still alive despite defeat to Mexico on Saturday but their coach Shin Tae-yong says there are problems with the country's domestic game that cannot be ignored.
Korea were beaten 2-1 by Mexico after goals from Carlos Vela and Javier Hernandez put the result beyond doubt in Rostov before Son Heung-min's stunning late strike.
Son was in tears after the match but his consolation goal could yet prove significant in Group F.
Germany's last-gasp win over Sweden later on Saturday means South Korea can still qualify if they overcome the world champions next week and the Swedes also lose to Mexico.
But that would mark an incredible turn-around given Tae-yong's side are yet to register a point from their opening two games in Russia.
"We have systemic problems," Tae-yong said. "We must think how we can improve our domestic league and work with young players. We lack experience. That doesn?t come overnight."
Son, the team's star player, was left with too much to do up front, often isolated, and without sufficient support to take on the Mexican defence.
But Korea had chances and the momentum of the game turned on another penalty, awarded against Jang Hyun-soo for a blatant handball and converted by Vela. It was the 14th spot-kick of the tournament.
"Our players, I think, played a game that they will not regret," Tae-yong added.
"All of the players became one and until the last minute they really did their utmost. I really am very grateful that they did their best until the very last minute."
Coach Shin Tae-yong says South Korea must improve their domestic league