Lamine Yamal became the eighth-youngest goalscorer in FIFA World Cup history at 18 years and 343 days.
The teenager scored the opening goal for Spain in the 10th minute of the match against Saudi Arabia.
Spain secured a convincing 4-0 victory, with Mikel Oyarzabal scoring twice and an own goal adding to the tally.
Yamal joined Pelé as one of only two players aged 18 or younger to score a team's first goal in a World Cup game.