Petr Cech has urged Chelsea to be aware of the dangers faced by Manchester United on Sunday.
United have Michael Carrick as caretaker manager, with Ralf Rangnick shortly set to join as interim boss on a six-month contract, and won their first game after sacking Ole Gunnar Solskjaer, 2-0 against Villarreal in the Champions League on Tuesday.
And Cech, 39, who works as a technical and performance director for the Blues, wrote in his column on the Chelsea website warning Thomas Tuchel's side not to be complacent against the Red Devils.