Torres was scheduled to return to the Barcelona clinic of Ramon Cugat—who carried out the initial operation on his damaged cartilage in January—on Thursday, after attending the 21st Hillsborough memorial service, but found his flight grounded as a result of the plume of ash generated by Iceland's Eyjafjallajökull volcano.
Torres, who has not resumed full training, is unlikely to feature against Gianfranco Zola's side without first consulting Dr Cugat.
Rafael Benítez, the Liverpool manager, said: "We are waiting. We have some problems with the flights, so we are working with him here and after that he has to see the specialist to be sure everything is fine. We have to wait and see how he progresses. He cannot be on the pitch now but he is fine."
Benítez was less candid when asked about his own, rather more long-term, future, despite assurances from the club's incoming chairman, Martin Broughton, that he expected the Spaniard to stay.
Benítez has persistently been linked with a move to Juventus, with his agent, Manuel Garcia Quilon, notably contradictory on the subject.
Though Garcia Quilon initially denied suggestions that he had met the Italian club's president, Jean-Claude Blanc, in Milan, a variety of conflicting reports have emerged.
Benítez would not be drawn on the matter, but he did welcome Broughton's declaration, made before the chairman and manager had even spoken to one another.
"Stability is important," Benítez said. "I will not speak too much about my future or that of the club because I have to do my job, which is to prepare us for games."
Past experience has taught the Spaniard, too, not to be drawn into false hopes over promised transfer budgets.