Ajax have confirmed coach Martin Jol has left the club by mutual consent.
The Amsterdammers lie fourth in the Eredivisie table, five points off leaders PSV Eindhoven.
Jol, who only took charge of Ajax in May last year, claimed the expectations at the Amsterdam ArenA were too high.
Ajax announced on their website that former Holland defender Frank de Boer would take temporary charge until the winter break.
Jol claimed the criticism the club have come in for for their stuttering form has caused unrest in the squad.
The former Hamburg and Tottenham boss told http://www.ajax.nl: "With pain in my heart I say goodbye to this wonderful club.
"We started something last summer that I would have finished. But I have come to realise that the expectations after last season were too high.
"We cannot meet such expectations.
"The amount of criticism that the club has had to endure daily has led to unrest in the club and among players.
"I take this decision consciously before AC Milan v Ajax (in the Champions League) is played (on Wednesday).
"The coming weeks are very important and I sincerely hope that something happens in the squad to make it in the short term a winning team."
The Amsterdammers finished second in the league last term, a point behind FC Twente, scoring 106 goals and with a staggering goal difference of plus 86.
They have struggled to repeat their end-of-season form in the early part of this campaign, though.
Jol had been expected to succeed Roy Hodgson at Fulham this summer, but, even though the Premier League club had agreed terms with the Dutchman, Ajax refused to let him leave.
Jol, though, made no secret of his frustration with the financial problems that forced Ajax to sell players over the summer, although they did hold on to star striker Luis Suarez.
And he has left the club just 17 games into the new campaign.
Ajax director Rik van den Boog paid tribute to the job Jol has done at Ajax.
He told http://www.ajax.nl: "What it happening today does not detract from the great season we experienced last year. The team reached the group stage of the Champions League. That was very important to us all. He has developed many players.
"Many games we won in spectacular fashion, scoring lots of goals and conceding few."
Jol's staff, including brother Cock and his assistant Michael Lindeman, have also left the club.
Caretaker De Boer is also the assistant to Holland coach Bert van Marwijk.
Ajax revealed they hope to announce a coaching staff in the new year.