Gianluca Curci is on stand-by ahead of the Juventus game after Marteen Stekelenburg was struck down by a virus.
The goalkeeper missed training on Thursday and there are fears that he may not recover in time for Sunday’s showdown.
The summer signing from Ajax has been a stable member of Luis Enrique’s side when fit so far this season.
If the Dutch international doesn’t recover then the Spanish boss will have to turn to the former Italian Under-21 international.
Back-up ‘keeper Bogdan Lobont is struggling with a knee injury, so the 26-year-old will be promoted from third-choice.
Curci, a product of the club’s youth system, returned to the capital outfit in the summer after spells at Siena and Sampdoria.
He hasn’t played a single minute of competitive football this season.