Chelsea boss Roberto Di Matteo has lost his job six months after winning the Champions League with the London club.
Confirmation of the Italian's sacking came less than 12 hours after Chelsea lost 3-0 to Juventus in Turin - putting their defence of Europe's biggest club competition in jeopardy.
In a statement, the club said: "Chelsea Football Club has parted company this morning with manager Roberto Di Matteo.
"The team's recent performances have not been good enough and the owner and the board felt that a change was necessary now to keep the club moving in the right direction as we head into a vitally important part of the season."
The Blues have failed to win any of their last four Premier League games, a run which has seen them slip from top to four points behind leaders Manchester City.
Abramovich reportedly instructed chairman Bruce Buck and chief executive Ron Gourlay to deliver the bad news, which they did at around 4am at the club's training ground following the team's return flight to London.
It is understood Di Matteo was far from shocked by the decision and had already said what amounted to a farewell to some of his players prior to the meeting.
The club said an announcement would be made shortly regarding a new manager.
Immediate attention will turn to whether the club can lure former Barcelona coach Pep Guardiola out of a year-long sabbatical from football.
Guardiola was a reported target for owner Roman Abramovich in the summer despite Di Matteo's Champions League and FA Cup success.
He had vowed to take a year's break from the game, but he is likely to be among the favourites to succeed Di Matteo on a permanent basis.
Former Liverpool manager Rafael Benitez is also being tipped to take over at Stamford Bridge.
Benitez was quizzed in Abu Dhabi this morning about whether an approach had been made.
He told Sport360: "You ask directly, I cannot answer directly.
"In football, a lot of people are talking so we will see what happens in the next few days.
"I am looking for a club that can challenge for trophies and Chelsea is one of these clubs.
"I have to talk with my agent and see what he has been doing the last couple of days. But I am just trying to go to a team that can win."
Di Matteo took charge of Chelsea - initially on a temporary basis - after the club sacked Andre Villas-Boas in March.
He rescued the club's ailing Champions League campaign and steered them against all odds to victory over Bayern Munich in the final on the German team's home turf, having already secured the FA Cup.
He was given a two year contract in June, but not before there had been major speculation over whether Guardiola would take over.
The season started well domestically but they have fallen slightly off the pace in recent weeks. Di Matteo has become the first top-flight manager to leave his post this season.
Newcastle manager Alan Pardew expressed his surprise at the Chelsea manager's departure.
He said: "I'm astonished, really. It just goes to show you how precarious we are as Premier League managers and you can't take anything for granted.
"The shock that should be there for the fans and the media should sound something to the owner of that football club because I don't know if that's the ninth manager or whatever it is in so many short years. It's just not fair.
"As far as I am concerned, he has done absolutely nothing wrong. His philosophy was to perhaps change the look of the team, which he has tried to do - that doesn't happen overnight - and he's won two competitions in less than a year, so it's unbelievable.
"He should walk straight into another job - probably at someone else's misfortune, unfortunately."
Manchester United defender Rio Ferdinand called the decision "madness" on his Twitter page.
He added: "The stability at our club is something our manager rarely gets praise for...don't underestimate that."