Spain have booked their place in the 2026 FIFA World Cup quarter-finals after substitute Mikel Merino scored a dramatic winner in the 91st minute in Arlington. The victory sends the European champions into the last eight for the first time since lifting the World Cup in 2010.
While Merino scored the decisive goal, De la Fuente believes Yamal delivered a performance that showed his growing maturity on football's biggest stage.
"For me, Lamine has played one of the most important matches of his life," De la Fuente said. "Beyond whether he was brilliant or not, for me it has been one of the matches that will help him grow the most."
Yamal arrived at the tournament managing a hamstring injury and started Spain's opening match against Cape Verde on the bench. He returned to the starting line-up for the 4-0 victory over Saudi Arabia and scored his first goal of the competition.
The 18-year-old continued his impressive form against Portugal, registering three shots, including two on target, while constantly stretching the Portuguese defence as Spain searched for a breakthrough.
De la Fuente also suggested Yamal's relentless running played a part in the injury suffered by Portugal full-back Nuno Mendes, who was forced off in the 56th minute.
"Lamine did a spectacular job. He suffered for the team, he defended for the team. When he had the ball, he always created doubt and uncertainty for the opponent. He generated a lot of fear," De la Fuente said.
"We still need Lamine in this World Cup, to keep growing and delivering these kinds of performances."
Spain now turn their attention to Friday's quarter-final against Belgium at Los Angeles Stadium. De la Fuente expects another stern test but insists every team remaining in the tournament has earned its place.
"Any opponent you face at this stage will have done enough to deserve being there, and whoever comes next will be an even greater challenge than those we have encountered up to now," he said.