Lamine Yamal's dazzling displays are helping Spain chase World Cup glory, but it is his three-year-old brother Keyne who is stealing hearts around the globe after his emotional celebration went viral during La Roja's 3-0 win over Austria.

Television cameras captured Keyne screaming with delight after Mikel Oyarzabal sealed Spain's Round-of-32 victory at SoFi Stadium with his second goal, with the clip quickly becoming one of the tournament's most shared moments.

Yamal, named the player-of-the-match despite not scoring, smiled when shown the footage and said his brother's joy meant more than any individual accolade.

"It moves me to see my brother happy and my mother living the life she's always dreamed of, my friends... In the end, it's what I want, it's a kid's biggest dream, besides football and everything else," Yamal said.

"He's everything to me, my brother, he's like a son to me, and I'm in love with him."

The 18-year-old produced another electric performance as Spain romped to a comfortable win over Austria and booked a place in the last 16, where they will face Portugal.

"I'm very happy in the end. As long as we win and advance to the next round, that's what matters," he said.

"How does the tournament motivate me? It's the biggest thing in football. There's nothing better than a World Cup. In the end, when a kid dreams of playing football, he dreams of playing for his national team, and here I am at a World Cup.

Yamal entered the World Cup still regaining full fitness after a hamstring injury in April and has yet to play a full 90 minutes in a match.

The 18-year-old said he is slowly regaining full fitness and hopes to help Spain win their second World Cup title.

"I'm focused on advancing to the next round and fulfilling my dream of winning a World Cup with Spain. Little by little, I'm starting to feel like myself again, making the runs I need."