London - West Ham sacked manager Slaven Bilic on Monday after a poor run of results that have left the club languishing in the Premier League's relegation zone.
The club announced the departure of the Croatian, appointed in June 2015, following a chastening 4-1 loss to Liverpool at the London Stadium on Saturday that leaves them 18th in the table and facing a fight for survival.
Bilic, who also played for West Ham, is the fourth Premier League managerial casualty of the season following the departures of Crystal Palace boss Frank de Boer, Leicester manager Craig Shakespeare and Everton's Ronald Koeman.
"West Ham United can confirm that Slaven Bilic has today left his position with the club," the Hammers said in a statement on their website.
The club hierarchy "believe a change is now necessary in order for the club to move forward positively and in line with their ambition", the statement added.
West Ham said an announcement on a new manager is due to be made over the coming days, with former Everton and Manchester United boss David Moyes widely expected to replace Bilic at the London Stadium.
Bilic's assistants Nikola Jurcevic, Edin Terzic, Julian Dicks and Miljenko Rak have also left the club with immediate effect.
Co-chairmen David Gold and David Sullivan said the decision to axe Bilic had been made with "heavy hearts".
The pair praised Bilic for his role in the move from Upton Park to the former Olympic Stadium, particularly the concluding win over Manchester United in the final home game of the 2015-16 campaign, which helped to earn a seventh-placed finish in his first season.
"During the summer, the board invested heavily signing the players Slaven believed would complete the squad he needed to push the club back towards the level we had reached in his first season, and we believe we have the players capable of doing that," they said in a statement posted on whufc.com.
"Sadly, performances and results have not been of the expected standard and, in recent weeks, we have not seen enough indication of the required improvement to give us the encouragement that things would change and we would meet our Premier League aspirations this season."
"We see this as an exciting opportunity to appoint a quality manager to the position to inject fresh ideas, organisation and enthusiasm into a very talented squad" they added.
Speaking after the chastening defeat at the hands of Jurgen Klopp's Liverpool on Saturday, Bilic admitted he did not know if he would be given time to turn things around.
"Of course I believe in myself," he said. "I definitely don't feel a broken man. I'm very strong. I believe in my dedication and my previous work. I know my value.
"On the other hand the situation for West Ham is not good. The club is above every individual and that includes me. Are we playing well? No, we are not. It's me that has to take responsibility."
West Ham have just two wins from 11 Premier League games, leaving them languishing above just bottom club Crystal Palace and Swansea.
The only bright spot in recent weeks was a notable victory against Tottenham at Wembley, when they came back from 2-0 down to win 3-2.
In his first season in charge, 2015/16, Bilic secured an impressive seventh-placed finish for West Ham, while last season they ended up in 11th spot.