Lee Jae-sung is a South Korean attacking midfielder and winger born in Ulsan on 10 August 1992. He began his professional career with Jeonbuk Hyundai Motors in 2014, winning multiple K League 1 titles and the AFC Champions League while also earning individual league honours. In 2018 he moved to Germany with Holstein Kiel, then joined Mainz 05 in 2021 and became a regular Bundesliga player. Lee has represented South Korea since 2015, reaching 100 senior caps and playing at FIFA World Cups.