Coutinho raised concerns at Camp Nou after it was confirmed that he will be out for between two and three weeks with a muscle problem.
His absence means Valverde will have to improvise a solution, with there no like-for-like replacement for the Brazilian in the Barca squad.
Atrhur's impressive performances in the middle of the park had seen Coutinho moved into the linking role between midfield and attack that he enjoys so much, but a more radical change may be on the cards on Sunday.
With Lionel Messi also facing a race against time to prove his fitness, the natural solution would have been to field Malcom on the left and Ousmane Dembele on the right. However, a bout of gastroenteritis for the latter may have put paid to that plan.
Should the Frenchman not make it in time to feature, it is likely that Rafinha's versatility will be put to the test once again as he is moved into a more advanced position that he is usually associated with.