Luiz Filipe Scolari faces his biggest club match in more than a decade this weekend - and he will have to do so without at least one of his most trusted men.
The cruciate ligament injury Michael Essien suffered on international duty for Ghana last week is so serious even his club don't really know how bad it might be. It will force the Blues boss to take desperate measures ahead of the crunch clash with the Premiership's other multi-billionaire side Manchester City.
With Michael Ballack and Jon Mikel Obi doubtful, things could barely be worse.
Nobody had better tell Scolari Jose Mourinho's first ever Premiership defeat with Chelsea came at the City of Manchester Stadium.
The reality now for Chelsea is that most of the current boss's debut season will take place without Essien. A statement issued by the club made this much clear: "A return to full fitness is not expected for several months.
"He has ruptured his anterior cruciate ligament and will undergo an operation as soon as the majority of the swelling has subsided. We expect this to happen in a week's time."
Chelsea also open their Champions League campaign for the season on Tuesday with the visit of Bordeaux. And five days later comes the visit of Manchester United.
As the transfer window ebbed away Chelsea seemingly made no effort to replace departing holding midfield legend Claude Makelele. When Chelsea last took to the field that slot was occupied by reserve right full back Juliano Belletti - resulting in a sucker-punch goal for opponents Tottenham.