Dimitri Payet's exit from West Ham United was the catalyst for Slaven Bilic downfall at the London Stadium, according to co-chairman Karren Brady.
The Croatian was dismissed after two-and-a-half years at the helm at the start of the week, after taking the Hammers into the Premier League bottom three.
Bilic's tenure began with West Ham achieving their best top flight finish for 14 years when they finished seventh and qualified for the Europa League - a performance inspired by top scorer Dimitri Payet.
But the France international failed to replicate those performances in Bilic's second campaign and went on strike in an effort to leave West Ham.
Payet eventually re-joined Marseille for £25m, according to The Daily Mail, in January 2017 and despite the arrival of Manuel Lanzini, Andre Ayew, Robert Snodgrass and Marko Arnautovic, Bilic has been unable to fill the void.
And Brady believes the saga regarding Payet triggered the end of Bilic's spell with the Premier League club, a decision which she admits was the board's hardest to make in 25 years.
"In his first six months, when Dimitri Payet was inspiring the team with his Gallic brilliance, Bilic sometimes looked pensive, as though he thought this was a lucky break and might not go on," the West Ham chief wrote in her column in The Sun.
"He never quite recovered after the player staged a strike and went back to Marseille.
"He began to run out of ideas as the team's initial defiance to Payet's behaviour faded and less than a year later the manager had also departed.
"As a board, we have sacked only five managers (including Slaven) of the nine we have worked with in that quarter of a century.
"This sacking was in some ways the easiest and in others, the hardest. We would liked to have kept Slaven but we couldn't. He understood."