Answer
Grzegorz Krychowiak achieved the most success in European club football while playing for Sevilla. The Polish midfielder joined the club in 2014 and helped them win the Europa League in 2015 and 2016. He also helped them reach the Champions League final in 2016, where they lost to Real Madrid. Krychowiak left Sevilla in 2016 to join Paris Saint-Germain, but he has not been as successful at the French club.