Avram Grant will take over as manager of Chelsea, with Steve Clark as his assistant, after the shock departure of Jose Mourinho late last night.
Former Israel coach Grant was recruited in the summer as director of football.
A statement released on the London club website this morning read: "Chelsea can confirm that Avram Grant and Steve Clarke will be in charge of the first team from today.
"The club is delighted that in Avram we have an experienced man who can come in at this difficult time to help deliver our objectives.
"In Steve we have a Chelsea man and he will be a crucial part of the management team going forward.
"Avram and Steve have our full support," the statement concluded. Grant and Clarke will not have an easy start in their new roles - their first game in charge on Sunday is against defending champions Manchester United at Old Trafford.
There was no mention of Mourinho in the statement and the club has erased his profile form the website.
He left the club by "mutual consent" yesterday, just a day after watching his side struggle to a 1-1 draw with Champions League minnows Rosenborg.
He is understood to have contacted five senior players yesterday afternoon to inform them of his departure, and by midnight the first team squad was aware of the news.
Mourinho had three years left on a contract worth £6.5 million a year.
At the time he signed that deal, Mourinho said: "My heart is with Chelsea and the fantastic group of players that I have, but the vision of the owner and the board for the future of Chelsea is also one I want to be a part of. I cannot imagine another situation or another club where I could be happier. I am totally behind this project."
He had won every domestic honour since his arrival in England in the summer of 2004 but the Champions League eluded him. Although he won the trophy with Porto in 2003, Chelsea were twice knocked out of the competition at the semi-final stage by Liverpool during his tenure.
They are now fifth in the Premier League, though only two points behind leaders Arsenal after six games, but their 1-1 draw with Rosenborg in their opening Champions League game on Tuesday night - played in front of less than 25,000 fans - appears to have been the final straw for Abramovich.
Mourinho, 44, has been at loggerheads with Abramovich since their disagreement over the lack of funds to sign players during last January's transfer window.
Mourinho's reluctance to play Andriy Shevchenko and the Russian's desire to bring in Grant from Portsmouth to work with the misfiring striker only served to heighten the tension.
The next step for Mourinho is unclear. He made one last farewell to Chelsea's players today and dashed past waiting reporters and photographers as he left the club's training ground in Cobham, Surrey, but refused to comment on his departure or future.
He has in the past made public his desire to manage the Portuguese national side and he is currently 1-3 with the bookies to take the post currently held by Brazilian Felipe Scolari. At the other end of the scale, he is 100-1 to take over from Steve Staunton as the Republic of Ireland boss.
