Spain take on France at Dallas Stadium for a place in the World Cup final, with Yamal saying the occasion is even bigger than the Euro final or any UEFA Champions League match he has played for Barcelona.
"This is number one," Yamal said. "It's the most important match I'm going to play."
The winger admitted he is enjoying every moment of Spain's World Cup journey and said he never imagined football would make him famous around the world.
"It's amazing that football has given me the chance to be recognised in places like Chattanooga," he said. "I could never have imagined walking through a town in the United States and people knowing who I am. I really value where I come from."
Yamal also dismissed suggestions that he had shown disrespect towards France after saying his opponents should fear Spain rather than the other way around.
"They asked me if I was afraid of France, and I said no," he explained. "We are European champions. It's football, as Jules Kounde said. That's all."
The Barcelona winger insisted he is feeling relaxed despite the importance of the occasion.
"I'm very calm," he said. "I'm even about to meet my brother to get a haircut.
"The match will be amazing. It's a game everyone wants to watch. Both teams attack and defend well, so it will be very close. But there's no pressure.
"I play the way I know how. When you give everything and people know that, you don't feel pressure."
Yamal brushed aside questions about lucky numbers after being asked about the significance of the number 19, which matches his shirt number, his age and the date of the World Cup final.
"I don't believe in that," he said with a smile. "And the necklace wasn't a gift. I bought it for myself."
Although he has scored only once during the tournament, Yamal said he is not worried about his personal statistics as long as Spain keep winning.
"Every tournament is different," he said. "It's not the coach's fault that I haven't scored five goals. That's just how football goes and I'm not concerned.
"When I was a kid, I watched World Cups where Spain were knocked out. Now we're winning and that's what matters. Hopefully I can score against France."
The teenager is convinced Spain have what it takes to lift the trophy.
"Of course we believe we can become champions," he said. "It won't be easy, but we all see ourselves as champions, just like the team did in 2010. Why not?"
Yamal also called for football to unite people after being asked about recent off-field controversy.
"We're going to play one of the most intense matches," he said. "But if football is good for anything, it's for bringing people together. Spain and France are good examples of that. That's what football should be about."
He also laughed off the online attention his younger brother has received during the tournament.
"He doesn't realise what's happening," Yamal said. "He just behaves the way he always does at home. When the camera is on him, he acts silly. I enjoy watching him because it makes me laugh."
The Spain star ended by responding to criticism of his recent performances.
"Since the Euros we've grown a lot as a team," he said. "I don't feel any pressure. If people think I'm not at my best, then they shouldn't expect anything from me. I just hope it's a great day."
