South Korea's Ki Sung-yueng announced his retirement from which sport on 31st January 2019?

On January 31st 2019, Football player Ki Sung-yueng announced his retirement from the South Korean national team. The midfielder though decided to retire after the 2018 FIFA World Cup in Russia yet decided to compete in the 2019 AFC Asian Cup, which held in United Arab Emirates, under the new national team coach Paulo Bento