Manuel Pellegrini has been fired by West Ham after 18 months in charge, paying the price for an alarming slump that has seen the Premier League team plunge from fourth place into a relegation battle.
The end for the 66-year-old Chilean at the Hammers came less than two hours after a 2-1 home loss to Leicester on Saturday night.
"It has become clear a change is required to get the club back on track in line with our ambitions this season," co-chairmen David Gold and David Sullivan said in a statement.
With an expensively assembled team, West Ham have won just two of their past 14 matches - losing the past four at home - and are a point and a place above the relegation zone.
"We felt it was necessary to act now in order to give the new manager as much time as possible," the co-chairmen added.
David Moyes, who was in charge on a short-term deal before Pellegrini arrived in the offseason of 2018, is among the favourites to take over.
The former Everton manager saved West Ham from relegation when he replaced Slaven Bilic in November 2017.
West Ham's players were booed off after the loss to Leicester, which played a virtual reserve team amid the busy period of festive fixtures, and it was clear fans had lost patience with Pellegrini, too.
He was a high-profile arrival at the London club, having previously managed Real Madrid and Manchester City, with whom he won the Premier League in 2014.
He oversaw an outlay of around $US200 million ($A286 million) on players in his time in charge - including then-record signings Felipe Anderson and Sebastien Haller.
Pellegrini led West Ham to a 10th-place finish in his first season but results have been poor this campaign, with the team embarrassingly losing 4-0 to third-tier Oxford United in the League Cup in September.
West Ham lost 29 of its 64 matches under Pellegrini.
Australian Associated Press