Diego Costa has been released from hospital following treatment for an illness, the BBC has reported.
The prolific Chelsea forward, who missed his side's 6-0 Champions League win at home to Maribor on Tuesday, was said to have been treated for a severe stomach bug following his return from international duty at Luxembourg, where he scored his first goal for Spain.
The 26-year-old had already been suffering from a groin strain and remains a doubt for the Blues' Premier League trip to Old Trafford on Sunday.
Widespread reports on Thursday morning said Costa's illness had necessitated a spell in hospital, but Chelsea have issued no statement.
Last week, Spain coach Vicente Del Bosque said Costa only plays for La Roja when he is fit after Chelsea boss Jose Mourinho urged the national team boss to allow the striker proper time for rest and recuperation.
Mourinho revealed that the player's ongoing muscle complaint had been aggravated by his starts in Spain's games against both Luxembourg and Slovakia.
Media in England and Spain have hinted at a club versus country row between the two former Real Madrid coaches -- but in an interview with AS, Del Bosque insisted that Costa only played for Spain when he was in the right condition to do so.