Yoon Jin-woo had never gone to Seoul World Cup Stadium to watch FC Seoul, the city’s team and the club that calls South Korean football’s symbolic home its own. But on Sunday night, he made the pilgrimage from the suburbs of Gimpo to see Manchester City and Atletico Madrid, two European clubs whose pull in South Korea rivals, and often overwhelms, interest in the domestic game. The 21-year-old and his friends were among 50,000 fans who filled the stadium with City’s light blue and Atletico’s red-and-blue shirts, turning a pre-season friendly into a vivid display of where much of South Korean football passion now flows. Yoon and his friends sounded like broadcast announcers, calling out every player’s name and reacting excitedly to every dribble and shot. Fans decked in Manchester City jerseys celebrate after a goal during the club’s friendly match with Atletico Madrid at Seoul World Cup Stadium on Sunday.