Surapong Kongthep has resigned as the head coach of Sukhothai and apologised for the team's failure to retain their place in Thai League 1.
Sukhothai were relegated to the second tier following a 1-0 defeat to Suphanburi in a match that decided which of the two sides would stay in the top flight on the final day of the 2020 season on Sunday.
The two others teams to be relegated from T1 were Trat and Rayong.
The Fire Bats needed only one point to escape the drop but conceded a goal in the last 10 minutes of the match when Leandro Assumpcao headed home to deliver the winner for hosts Suphanburi.
Under Surapong, Sukhothai collected only 28 points from their 30 games -- their lowest haul since being promoted to the top flight in 2016.
The 42-year-old Surapong posted a message on his Instagram account yesterday, saying: "I would like to thank Dr Anongwan Thepsuthin, president of Sukhothai FC, Mr Somsak Thepsuthin and Mr Ketpong Kullanartsiri who all looked after me and the team very well throughout my 14 months with the team. I would like to apologise to them that I could not help the team to achieve their goal. I am therefore terminating my contract as the head coach of Sukhothai FC from today."
Meanwhile, Thai League 2 champions Nongbua Pitchaya and runners-up Chiangmai United have been promoted to the top league. Teams finishing third to sixth will be involved in a home-and-away play-off event with the winners earning promotion to T1.
First leg home-and-away play-offs will pit Chainat (sixth place) against Nakhon Pathom United (third) and Phrae (fifth) against Khon Kaen United (fourth).