Atletico Madrid's problems continue to mount, as coach Quique Sanchez Flores was unable to preside over Monday's training session due to illness.
Early indications are suggesting that the virus is the H1N1 strain, although the results of the tests will be revealed in the coming hours.
It remains a possibility that Sanchez Flores is only suffering from a common cold, in which case he will be present for Atletico's key league match this weekend against Deportivo La Coruna in the Riazor.
The trainer will have to rest for at least three days, and may be able to return to his duties on Thursday, according to Atletico's official Web site.
Diego Forlan, Simao, Sergio Asenjo and David De Gea were all absent from Monday's training due to international commitments, while Roberto was not at the session due to his partner having given birth to a child hours earlier.