Both teams enter the Group A clash at the Guadalajara Stadium on Thursday with three points following opening victories, with South Korea beating the Czech Republic 2-1.
While Mexico defeated South Africa 2-0 to start their campaign, Aguirre noted that 10 of his players were making their World Cup debuts and appeared physically and mentally tight under the pressure of the home crowd.
"I granted them the benefit of the doubt for the nervousness of a debut," Aguirre said. "But I told them I can no longer allow a player, because of the stage, to be unable to make a three- or four-metre pass or a movement they have trained for."
Aguirre identified South Korea's transition speed as the primary threat, citing a friendly between the two nations in September where Mexico struggled to contain their counter-attacks.
"The speed of the Koreans going forward - we have trained on how to nullify it," Aguirre said. "We have to be attentive to the 'vigilance' when we are attacking. If there are two Koreans, there must be at least three Mexicans."
Tactical breaks
The 67-year-old also addressed the growing debate surrounding FIFA's mandatory hydration breaks.
While introduced to protect players from the North American summer heat, the three-minute pauses have become a tactical flashpoint, with critics arguing they kill the momentum of dominant teams.
"We take advantage of the rules," Aguirre said. "It allows you to give instructions while the players drink water. I use those breaks to correct things I see; it's actually helpful for us coaches because we don't have to shout across the field anymore."
The coach noted that the modern game was increasingly shaped by such new rule modifications and technological aids.
"It is another type of football than the one I played," Aguirre said. "Between the VAR and the technological evolution where they send you images at halftime, I think it all adds up to better football."
Despite the advances in the game, Aguirre noted that the unpredictability of the World Cup remains constant, citing the parity seen in early results.
"I have 50 years in this blessed football and I still feel a strange nervousness before every game ... The day I don't feel that, I'll go home."
FIFA World Cup 2026
The 2026 World Cup is taking place from June 11th to July 19th in the United States, Canada and Mexico. The tournament features 48 national teams and is played at 16 modern stadiums.
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