Lamine Yamal turned 19 on Monday with diamonds around his neck, mischief in the family and the biggest match of his life ahead but the Spain forward's clearest message before the World Cup semifinal against France was not about goals, gifts or fame.

Asked about former Spanish Prime Minister Mariano Rajoy's controversial remark that France were a great team but "did not have any French players", Lamine, son of a Moroccan father and Equatorial Guinean mother, said football should be a bridge.

"Tomorrow we'll play a brilliant match but if football serves any purpose it's to bring people together," Lamine told reporters in Dallas.

"France and Spain are examples of integration. That's what football is all about: integration. Not talking about what someone else has said."

It was a measured answer from a player still young enough to be asked about birthday presents and famous enough for his family to be swept into the tournament glare.

Lamine smiled when asked about his three-year-old brother Keyne, whose spontaneity in front of television cameras has made him one of Spain's unexpected World Cup attractions.

"My brother doesn't realise," Lamine said. "He does what he does at home, and when the camera focuses on him, he gets up to mischief.

"I like it when people like him. It's fun to see him on screen."

Lamine also arrived at the news conference wearing an extravagant diamond necklace, his birthday present to himself, on the eve of a game he described as "the most important match of my life".

Yet Lamine said he was not fretting over his own numbers, despite having scored only once at the tournament so far.

"Every tournament is different," he said. "I'm not worried about having scored just one goal in the World Cup so far. We're winning.

"I've seen World Cups where Spain were knocked out, and so far that hasn't happened. I hope to keep playing matches so I can score."

Spain face France in Dallas for a place in the World Cup final, with Lamine's birthday week offering another layer of theatre around a player who seems increasingly comfortable carrying attention that might flatten others.

"And it’s going to be a great match. A match that everyone was hoping would happen. Both teams will attack and defend. It’s sure to be a very evenly matched game," he said.

For now, he wants football to do the talking — preferably loudly enough to carry Spain at least one match further.