David Wagner performed a minor miracle getting Huddersfield into the English Premier League and then keeping the team there for a season.
With the dream starting to turn sour, the German-born American coach felt he could do no more.
Wagner stood down as manager of the Premier League's bottom side on Monday, with chairman Dean Hoyle saying the coach "came to us and made it clear that he needs a break from the rigours of football management."
After just two wins from 22 games, Huddersfield are eight points from safety with 16 games remaining.
The Terriers' main problem has been a lack of goals with just 13, with the absence since early December of injured Socceroos playmaker Aaron Mooy a bitter blow.
"I had no intention of sacking David this season," Hoyle said, adding that, under Wagner, Huddersfield has "achieved things on the football pitch that surpass anything in modern memory."
Wagner, a former US international, arrived at the northern English club in 2015 from Borussia Dortmund, where he was the reserve team coach, and only just managed to keep Huddersfield in the second tier.
From that 19th-place finish out of 24 teams, Wagner worked wonders on one of the smallest budgets in the division and Huddersfield won promotion to the top flight for the first time since 1972.
Wagner then produced possibly a more impressive feat to keep Huddersfield in the EPL.
Wagner has struggled for positivity this season, however, with Huddersfield having lost 15 league games with the goalless draw at Cardiff on Saturday ending an eight-game losing streak.
Hoyle said it was a "truly joint decision" between Wagner and Huddersfield's board.
Wagner offered to stay on until the end of the season if the board preferred but, after more discussions, "we all now feel that the time is right to part ways," Hoyle said.
Hoyle confirmed under-23s coach Mark Hudson will take charge for Sunday's league game against champions Manchester City.