month later. The 2015 calendar year began in March with a match against Turkey, ending in a 1–1 draw. On 29 June 2015, Hiddink left his position. Two days later, he was succeeded by his assistant, Danny Blind. It was unknown for a long time whether Hiddink was fired or left his position voluntarily, but on 21 November 2015, he said, whilst on vacation in France, that he was fired from the post. Return to Chelsea On 19 December 2015, Hiddink was appointed first-team manager of English side Chelsea until the end of the 2015–16 season, following the dismissal of José Mourinho; he joined the club in the same capacity he did back in 2009. After being made interim manager, Hiddink spoke, saying he was "excited to return to Stamford Bridge" and "I am looking forward to working with the players and staff at this great club and especially renewing my wonderful relationship with the Chelsea fans." After the home draw against Stoke City, Hiddink set a new record for the longest unbeaten streak as a new manager in the Premier League with 12 games unbeaten. Chelsea ended the season in tenth place in the Premier League, climbing six positions from 16th upon Hiddink's arrival. China U21 On 10 September 2018, Hiddink took over the China under-21 national team but was fired in September 2019 after a string of disappointing results, culminating with a 2–0 defeat against Vietnam under-22 men's team. The coach of the Vietnamese team coincidentally was Park Hang-seo, assistant coach of South Korea's national team in the 2002 World Cup under Hiddink. Curaçao and retirement from management On 21 August 2020, Hiddink was appointed manager of the Curaçao national team. After failing to lead the nation to 2022 FIFA World Cup qualification, Hiddink contracted COVID-19 in 2021, prompting Patrick Kluivert to step in as interim manager of the team. On 9 September 2021, Hiddink officially stepped down as head coach of Curaçao and announced his managerial retirement at the age of 74. Temporary end of retirement for a return to Australia Hiddink came out of retirement to assist his former Socceroos assistant, Graham Arnold, for Australia's two-match friendly series against New Zealand, as regular assistant coach René Meulensteen was scouting the Socceroos' Qatar 2022 opponents in Europe. The temporary arrangement formed part of the Socceroos' centenary celebrations. Hiddink was on the Australian bench for their 1-0 win