Portsmouth striker Lomana LuaLua is recovering in hospital after being told he was suffering from malaria.
The Fratton Park club fear he could be out for up to six weeks.
He missed last week's defeats at Gillingham in the Carling Cup and Bolton in the Barclays Premiership with what club officials thought was a bout of flu, collapsed at training on Monday and was rushed to hospital.
LuaLua, 24, is thought to have contracted the virus while on international duty for the Democratic Republic of Congo against the Cape Verde Islands earlier this month when he captained his country to a 2-1 win.
A spokeswoman for the Queen Alexandra Hospital in Corsham, Hampshire said it was unlikely the player would be discharged soon.
The spokeswoman said: "He is feeling fine and it is now a matter of him having more of the appropriate treatment to get him better. It can be a very debilitating illness."
