Jurgen Klinsmann sent shock waves through the Bundesliga as he stepped down as manager of Hertha Berlin barely 10 weeks after taking charge.
The 1990 World Cup winner announced his decision in a post on Facebook, three days after Hertha crashed to 3-1 defeat at home to Mainz which left them just six points above the relegation zone.
"After long consideration, I have decided to give up my position as head coach and return to my original, long-term role on the club board," Klinsmann, 55, wrote.
"I am convinced that Hertha will stay up."
In the post, he suggested there was a lack of trust from the club hierarchy.
"In a relegation fight, unity, solidarity and concentration on the essentials are the most important things. If they are not guaranteed, I can't reach my potential and live up to my responsibility as coach."
Klinsmann's decision is a major blow to Hertha, who were looking at him to navigate their way out of the danger zone and towards Champions League.
"We were very surprised by what happened this morning. There were no previous indications of this decision," said sporting director Michael Preetz.
The club announced Klinsmann's assistant Alexander Nouri would take over as interim manager with immediate effect.
The former Germany boss was brought in as a short-term solution in November after a horror start to the season under Ante Covic.
After taking over, he became the face of Hertha's bold ambition of establishing themselves at the top of the league following a new deal with investor Lars Windhorst.
Shortly after his arrival, Klinsmann said that Berlin deserved "a super club" and that Hertha should target Champions League football within three years.
According to German daily Bild, Klinsmann may have resigned due to a dispute with the club over his future in the Hertha dugout. The newspaper claimed that Klinsmann was 'frustrated' by the club's reluctance to guarantee his job beyond the summer.
However, the former Bayern Munich star will retain his place on the club board, a position he held before taking over from Covic.
As Germany manager, Klinsmann took the national team to the 2006 World Cup semi-finals on home soil. He later coached the US national men's team from 2011 to 2016, leading them to the World Cup finals in Brazil in 2014.
Hertha was his second job in club football, following an ill-fated spell at Bayern Munich in 2009.
