Courtois progressed through the youth system of Genk, and aged 18, he played a key role in the team's Belgian Pro League victory. In July 2011 he joined Chelsea for a reported £8 million, and was immediately loaned to Atlético Madrid. In three seasons there, he won the Europa League in 2012, the Copa del Rey in 2013 and the La Liga title in 2014. He also won the Ricardo Zamora Trophy for best goalkeeper in La Liga, for his performances in his two latter seasons. Courtois returned to Chelsea in July 2014, and in his first season he helped them win the League Cup and the Premier League title. Two years later, he won the Premier League Golden Glove as Chelsea again won the league. In 2018, Real Madrid signed Courtois for £35 million, becoming La Liga's most expensive goalkeeper, surpassing the record set by Jan Oblak. He won a second La Liga title and a third Zamora trophy in 2020.