Having bounced back from their worst league run for almost 15 years at the start of 2011, Chelsea have again slumped to fifth in the table after failing to win - or score in - either of their last two games. There are now just 12 matches remaining for the champions to claim a place in the top four.
Speaking at UEFA Headquarters for the official handover of the Champions League trophy to Heineken for its two-month tour of Asia, former France defender Desailly said: "Unthinkable, yes, because they need the Champions League."
Ex-England left-back Le Saux added: "To imagine them not qualifying is unthinkable.
"If they don't finish in the top two or three there'll be reasons for that, which I would think would be quite easy to explain."
Those reasons range from the departure of experienced players in the summer to injuries to key men, the sacking of assistant manager Ray Wilkins and the disruption caused by the record-breaking signings of Fernando Torres and David Luiz.
All this, as well as Ancelotti leading the club to an historic double in his first season at the helm, have made the Chelsea manager more bulletproof than his predecessors, according to Desailly.
"The difference between Ancelotti and the others is that he won (the double)," said Desailly, who nevertheless believes the Italian is not without blame for the club's problems this term.
"He needs to read his players a bit better and fit them into his own tactics."
Source: PA
Source: PA