Millwall boss Mark McGhee has left the club after his contract was terminated by mutual consent.
McGhee has paid the price of poor performances at the start of the season, culminating in the 1-0 home defeat by Preston on Tuesday.
Assistant boss Achie Knox has also had his contract terminated by mutual consent despite the Lions sitting eighth in Division One and just six points behind leaders Sheffield United after 14 league games.
Chairman Theo Paphitis told the club website: "Last season was a frustrating one for the club and whilst expectations were high at the start of the current campaign, we have struggled to live up to them."
McGhee joined Millwall three years ago and led the club to promotion from the Second Division during his first season in charge.
The Scot followed up that achievement by helping the Lions reach the First Division play-off semi-finals the following season, where they lost to Birmingham over two legs.
But the former Wolves boss endured a difficult campaign last season, finishing 10 points outside the top six after taking two points from their first five games.
Paphitis added: "We met with Mark after the Preston game on Tuesday night and he agreed that it is in the best interests of both parties that there is a parting of the ways.
"The meeting was very amicable and I would like to thank Mark for his
contribution to Millwall.
Took over: 25/09/2000
Previous clubs: Reading, Leicester, Wolves
"He took over in September 2000 with the brief to get the club into the First Division that season which he duly achieved.
"We then enjoyed a very successful first season at this level, reaching the play-offs the following year.
"Last season was a frustrating one for the club, and whilst expectations were high at the start of the current campaign we have struggled to live up to them.
"There will be an announcement during the course of the day with regard to a caretaker manager and we will be inviting applications for a permanent manager shortly."
Lions defender Stuart Nethercott believes Millwall bowed too easily to pressure from the club's fans.
The Lions defender said: "I'm very surprised. We're 14 league games in. Is that a fair enough ride given that we're sitting in eighth spot?
"The supporters had just had enough and the chairman reacted to it
and this happened by mutual consent. It's a sad day."