Former fans' favourite Gianfranco Zola has warned Chelsea that their "fragile" players are running out of time to turn around a disappointing season.
The Blues' 3-1 defeat to Napoli in the first-leg of their Champions League last-16 tie signalled a fifth game without a win.
Andre Villas-Boas's side now face likely elimination from Europe's premier club competition and qualification for next season's tournament is dependant on them improving their domestic league position of fifth.
Zola, working as a Sky Sports pundit for the game in Naples, explained that Chelsea's players must toughen up mentally and do it fast.
He said: "I think they will have to analyse what is going on and to sort it out quickly.
"Especially psychologically, at the moment they are a little too fragile and you cannot afford that, especially at this stage of the season.
"You have to know what you're doing and you have to do it 100% convincingly."
The 45-year-old spent seven years at Stamford Bridge as a player between 1996 and 2003, scoring 80 goals.
