Manager Roberto Di Matteo has parted company with Chelsea, the club has announced.
Di Matteo won the Champions League and FA Cup as caretaker manager last season and was given a two-year deal in June.
But in the wake of the 3-0 defeat to Juventus, which has left the Blues on the brink of a Champions League exit, he has left Stamford Bridge.
"The club will be making an announcement shortly regarding a new first-team manager," a statement said.
Owner Roman Abramovich has made contact with former Liverpool manager Rafael Benítez to gauge his interest in taking charge at Chelsea on a short-term basis.
The club's Russian owner made contact with Benitez even before the defeat in Italy as he assessed his options.
After an impressive start to the season, the Blues have won two of their last eight games.
They sit third in the Premier League table, four points behind leaders Manchester City, who they host at Stamford Bridge on Sunday.
Chelsea could become the first-ever Champions League holders to exit at the group stage the season after.
The statement continued: "The team's recent performances and results 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 club faces a difficult task ahead in qualifying for the knockout stages of the UEFA Champions League as well as maintaining a strong challenge for the top of the Premier League while competing in three other cup competitions.
"Our aim is to remain as competitive as possible and challenge strongly on all fronts."
Former West Brom manager and Chelsea player Di Matteo, who had been working as assistant manager at Stamford Bridge, replaced Andre Villas-Boas in March.
He took over in the wake of Chelsea's 3-1 defeat to Napoli in the first leg of their Champions League last-16 tie.
But they overturned that deficit with a 4-1 win at Stamford Bridge and secured a 2-2 draw at Barcelona in the semi-final second leg despite having John Terry sent off in the first half at the Nou Camp.
After beating Liverpool 2-1 in the FA Cup final, they beat Bayern Munich in a dramatic penalty shoot-out in the Champions League final.
They finished sixth in the Premier League and Abramovich waited until June to give Di Matteo the job on a permanent basis.
And after the arrivals of Eden Hazard, Oscar and Victor Moses, they suffered just one defeat in their opening 12 matches before the recent downturn.
Abramovich is now looking for a ninth manager since he took over at Stamford Bridge in 2003.