"As important as individual skills are, I think confidence is just as crucial," Son said, as reported by the Korea Times.
"I think our confidence may have been low after losing twice in March (to Ivory Coast and Austria), and we will try to build on this and keep the momentum going."
The captain emphasized that a high-scoring victory should not be dismissed lightly, regardless of the opposition.
"Regardless of opponents, it's not easy to win 5-0," Son added. "So I hope people don't take this for granted.
The players deserve credit and I think we're moving in the right direction."
Son urged his teammates to maintain perspective and stay grounded as they prepare for higher stakes in the upcoming tournament.
"We should all try to stay humble. We won 5-0 today but we have also lost 5-0 before," Son said.
"We have even bigger matches awaiting us and we shouldn't get too excited when we win or too disappointed when we lose.
We have to fix whatever we need to fix going forward."
When questioned about the specific tactical areas that required refinement before the tournament, Son declined to elaborate publicly.
"It's something we will talk about internally because we want to keep this group tight," he said.
"I don't think it does us any good to discuss whatever we need to improve publicly."
Son concluded by prioritizing collective success over individual scoring milestones, despite nearing the all-time Korean men's goal-scoring record.
"I think it's more important for me to play well for the team, and it doesn't always have to be about scoring goals," Son said.
"Making sacrifices for the team and doing whatever the team needs is my favorite thing to do, something that I've valued more than anything throughout my career."
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South Korea is scheduled to play its final pre-World Cup warmup match against El Salvador on Wednesday at BYU South Field before opening its tournament campaign against the Czech Republic on June 12.
