Real Madrid beat Barcelona in a new-look El Clasico to go top of La Liga’s table and leave Ronald Koeman’s side down in eighth.
It was the first Clasico without Barca icon Lionel Messi or Real legend Sergio Ramos – who both joined Paris St-Germain in the summer – since 2004.
Sergio Aguero scored his first Barca goal but it was almost the last kick.
Alaba’s goal was the best of the game. The former Bayern Munich defender won the ball from Barca striker Memphis Depay on the edge of his box before starting a counter-attack.
He finished it off by running onto Rodrygo’s pass before slamming a shot across home keeper Marc-Andre ter Stegen into the far corner.
It was his first goal for Real Madrid, who he joined in the summer, on his El Clasico debut.