Jurgen Klinsmann has stepped down as Hertha Berlin's head coach after just 10 weeks at the helm in a move that the club said had taken them by surprise.
The former Germany and USA soccer team coach made the announcement on his Facebook page on Tuesday. The 55-year-old Klinsmann added in the post that he would return to sitting on the club's advisory board, a role he was appointed to shortly before he took over as head coach.
"We were very surprised by what happened this morning," said Hertha sporting director Michael Preetz in a statement on the club's website.
"There were no previous indications of this decision, especially after the support shown throughout a busy winter transfer market in regards to signings. We will provide further information as the situation develops."
Hertha is 14th in the Bundesliga -- six points above the relegation zone. The Berlin club had sat level on points with Fortuna Düsseldorf in the relegation playoff position when Klinsmann took over in November.
In a open letter to fans on his Facebook page, Klinsmann paid tribute to the club and its fans, saying: "I would like to express my sincere thanks to all players, fans, spectators, coaches and employees of Hertha BSC for the support, the many encounters and the exchange in the past 10 weeks.
"This time was extremely exciting for me and brought many interesting new insights. The club and the city have grown dearer to my heart."
However, the 55-year old also said he had encountered "trust" issues that had frustrated him.
"As head coach, however, I also need the trust of the people involved for this task, which has not yet been completed. Unity, cohesion and focus on the essential are the most important elements, especially in the relegation battle.
"If they are not guaranteed, I cannot exploit my potential as a trainer and therefore cannot live up to my responsibility.
"Therefore, after much deliberation, I came to the conclusion that I would give my position as head coach at Hertha."
The 10-week stint was Klinsmann's first managerial role since he was sacked as coach of the US men's team in November 2016.
While in charge, Klinsmann led Hertha to three wins, three draws and four losses, which included a narrow extra-time defeat by Schalke 04 in the German Cup last week.
"In November, we agreed to the club's wish to help out in a difficult time with a highly competent team," said Klinsmann.
"We were progressing really well in a relatively short period of time and have managed to put six points between us and the playoff spot, despite difficult games, thanks to the support of many people. I'm convinced Hertha will achieve its goal of remaining in the Bundesliga."
Hertha's next game is away at Paderborn on Saturday, and Klinsmann's assistant Alexander Nouri will take charge of as interim head coach.
After an illustrious career as a player, which included winning the 1990 FIFA World Cup with West Germany, Klinsmann has worked sporadically as a manager.
He took Germany to third place in their home world cup in 2006, and after a short stint in charge of Bayern Munich from 2008 to 2009 -- which then captain Phillip Lahm called a "failure" -- Klinsmann spent five years in charge of the US men's soccer team from 2011 to 2016.
Klinsmann enjoyed relative success with the team, reaching the round of 16 at the 2014 World Cup. However, he was sacked in 2016 after a series of poor performances left the team struggling to qualify for the 2018 World Cup in Russia.