The Sweden international finished the game with a hat-trick, becoming the youngest player in the San Sebastian club's history to score three goals in a single LaLiga game.
Earlier in the game, the 21-year-old equalled another club record by scoring in a sixth LaLiga game in a row, joining John Aldridge and Darko Kovacevic to become just the third La Real player to do so.
1 - Alexander Isak 🇸🇪 has scored in each of his last six LaLiga games for @RealSociedadEN (seven goals), becoming the youngest player to do so in the competition in the 21st century. Machine. pic.twitter.com/lzOcayI6m5— OptaJose (@OptaJose) February 21, 2021