Lionel Messi missed Barcelona training on Wednesday morning after complaining of feeling unwell after the 3-1 Copa del Rey defeat to Real Madrid at the Camp Nou.
Messi was again well below par in the second leg, and was completely outshone by fellow superstar Cristiano Ronaldo, as Madrid comfortably progressed 4-2 on aggregate to the Copa final, where they will face either Sevilla or Atletico Madrid in May.
Barca's concerns are more short term, with Messi unable to attend training. however he is expected to be fit to play in Saturday afternoon's Primera Division clash with Madrid at the Bernabeu.
"Leo Messi did not train this morning with his team-mates at the Ciudad Deportiva Joan Gamper," the statement said. "The Argentine player had a fever and felt generally unwell. The first-team doctors visited Messi at his home, where he was given the relevant medication and it was recommended he rest.
"The team has a day off on Thursday, and it is expected that Barca's '10' will be able to train on Friday afternoon, which will be the last session before the La Liga Clasico at the Bernabeu."
Barca also said that Xavi Hernandez did not take part in the scheduled recuperation session on Wednesday morning, instead doing some physiotherapy work away from the main group.
After training had finished Andres Iniesta spoke with reporters and admitted that the team seemed to be suffering a physical dip which was affecting their energy and accuracy on the pitch, something also alluded to by stand-in coach Jordi Roura in his post-game press conference on Tuesday night.
"It is not that we cannot do it, but that we try and for some reason the opponent overcomes us," Iniesta said. "In these recent games, which were important, we were missing something. When a team does not work, it is about everything and everyone. From back to front and front to back. Some opponents play differently and we must adapt."
Iniesta said the team had seemed affected in the same way during last week's 2-0 Champions League last-16 first leg loss in Milan.
"In these two games we have lacked freshness and accuracy in attack," he said. "We have missed that sensation of being an infallible team. We must get that sensation back. When we are on a good run we create more chances. That is what made us the team we are.
"When things do not go well, there is something we are not doing well. We should not make the mistake of not looking at ourselves. Things must be looked at in the coming days. For this we have the coaches and we trust in them."
Iniesta would not be drawn on whether this change should involve him being switched into a more central midfield role from his current usual starting position on the left wing.
"Everyone knows what I think, but I must perform at my best wherever I am put," he said. "The coach makes the decisions and there is no other explanation. I do not start debates. My natural position is an 'interior' [inside forward / creative midfielder], but what matters to me is that the team wins. That is my only concern in each game."
While Saturday's game at the Bernabeu is important, the Spain international said the main focus now must be a comeback against Milan, and he is convinced it is possible.
"We must go out against Milan, from the first minute, as if our lives were on the line," he said. "We must try and keep the distance in La Liga and we have an important game at the Bernabeu. I have no doubts. The tie against Milan is very difficult, but we will get through. We need to be convinced of that. At the moment, La Liga is well under control."