2013 AFC Coach of the Year award, becoming the second South Korean in succession to win the individual accolade following the previous year's winner Kim Ho-kon. Choi left the club in June 2016. On June 21, 2016, FC Seoul appointed Hwang Sun-hong as their eleventh manager in the club's history. On November 6, 2016, FC Seoul won their sixth K League title after defeating Jeonbuk Hyundai Motors 1–0 in the final round of the season. A period of oscillation (2017– ) Hwang Sun-hong resigned on April 30, 2018. In the 2018 season, FC Seoul finished in eleventh place and had to play the K League promotion-relegation playoffs for the first time in their history. In the playoffs, they defeated Busan IPark 4–2 on aggregate, thus staying in the top flight. On October 11, 2018, Choi Yong-soo was appointed as the twelfth manager in the club's history, having previously managed the club between 2011 and 2016. However, Seoul, which had been under fire since the beginning of the 2020 season, was mired in five consecutive losses for the first time in 22 years, disappointing fans. This just represented the start of a pretty complicated year for the team, as they went through a long-lasting crisis both on and off the pitch: they suffered several debacles throughout the season, such as a 0-6 away defeat against Daegu in the sixth round of K League 1 and a 1-5 home defeat against Pohang in the quarter-finals of the FA Cup; some of the squad's key players, such as returning Brazilian striker Adriano (a record-breaking and prolific goalscorer in his previous spell at the club between 2015 and 2016) and Spanish defensive midfielder Osmar Barba, didn't manage to show their full potential, due to inconstant performances or injuries; following a new departure by Choi Yong-soo, three different caretakers took turns managing Seoul, with Park Hyuk-soon replacing Kim Ho-young after just a month and guiding the team to the end of the K League season (which they finished in 8th position, after participating in the relegation group), before being substituted by Lee Won-jun; under the management of this last coach, the team made a promising start in the group stage of AFC Champions League, even obtaining a thrashing 5-0 victory against Thai outfit Chiangrai United, but then proceeded to lose all of their last three matches, thus being eliminated from the tournament. A very difficult