David Moyes is expected to be appointed the next West Ham manager, Sky Sports News understands, after Manuel Pellegrini was sacked following defeat to Leicester.
The 66-year-old Chilean was under increasing pressure during an awful run of form since a 4-0 defeat to Oxford United in the EFL Cup in September.
- Leicester win seals Pellegrini fate
- What went wrong for Pellegrini?
- Transfer Centre - latest news and reaction
- Premier League table - Hammers languishing
Following a promising start to the campaign, the Hammers embarked on a run of nine league defeats and just two wins in 13 matches, losing at home to Newcastle, Tottenham and most recently the Foxes.
They sit just a point above the relegation zone heading into the New Year and, after dismissing their manager just 18 months into a three-year deal.
Co-owner and chairman David Sullivan said on Saturday night: "It is with great disappointment that we've had to make this decision.
"Manuel is a gentleman and it has been a real pleasure to work with someone of his calibre. However, it has become clear that a change is required to get the club back on track in line with our ambitions this season.
"We felt it was necessary to act now in order to give the new manager as much time as possible to try and achieve that goal."
Moyes saved the Hammers from relegation during the 2017-18 campaign before being replaced by Pellegrini after his short-term deal expired at the end of that season, and they are readying themselves to re-appoint the Scot, who has been out of work since.
Moyes was recently linked with an interim role at another of his former clubs in Everton to replace Marco Silva, but they instead turned to Carlo Ancelotti.
'Pellegrini exit inevitable, Moyes man for job'
Former West Ham striker Tony Cottee says it was inevitable Manuel Pellegrini was dismissed and believes former boss David Moyes would be the ideal candidate to succeed the Chilean.
"I'm not surprised, West Ham were really poor against Leicester and it's been coming for the last three or four weeks or so," Cottee told Sky Sports News.
"He had a stay of execution with the victories over Chelsea and Southampton but overall it's been a really poor run of form. The board have obviously looked at it with a big game coming up on New Year's Day against Bournemouth and made a decision.
"They've tried a so-called top foreign manager, personally I think they need to go back to someone with a bit of passion, who understands the Premier League but more importantly the football club.
"I've already mentioned David Moyes, I think he could come in and do that job - there's also Chris Hughton who understands the football club and grew up supporting them.
"Whoever it is I think it needs to be someone available, come into the club and hit the ground running, sort out the defence and starting getting points on the board and move towards safety."
Sky Sports' Ben Grounds and Oliver Yew:
'West Ham allowed Adrian to depart to Liverpool in the summer, but it is a decision which will haunt Pellegrini after Roberto's struggles in the absence of first-choice goalkeeper Lukasz Fabianski, who suffered a serious hip injury in the 2-2 draw at Bournemouth in September.
'Fabianski is not the only important player who has been sidelined by injury this season. Michail Antonio's pace and physicality made him a big miss during his time on out between August and November. But Pellegrini did not help matters with his team selections either.
'Away victories at Chelsea and Southampton gave Pellegrini a little longer than many expected, but it felt inevitable that West Ham would sack him after they were beaten by a second-string Leicester side on Saturday.
'It was the Hammers' fourth straight home loss, leaving them just one point above the relegation zone. It was the final straw for the club and its restless supporters, who jeered Pellegrini's decision to substitute record signing Haller, rather than give him some support in attack.
'"Some of the decisions the manager makes baffle me," Cottee admitted. "Haller was playing on his own. You can't play one up front at home; have a go. When they went behind they didn't look like getting back in it and defensively they were a shambles."'