Madrid - Atletico Madrid striker Mario Mandzukic is doubtful for his side's Copa del Rey last 16, second leg away to holders Real Madrid on Thursday due to a fever.
The Croatian did not train with his team-mates on Wednesday as the Spanish champions finalised their preparations to defend a 2-0 first leg lead.
"Mandzukic couldn't train because of a fever, so we will wait until tomorrow before taking a decision," Atletico boss Diego Simeone said on Wednesday.
The absence of Atletico's top scorer this season could open the door for Fernando Torres to make his second start since returning to his boyhood club earlier this month.
Torres has failed to impress in his two outings since returning to Spain, against Real Madrid and Barcelona in the past week, but Simeone remains confident his former team-mate will come good.
"Before he was a boy and now he is a man, he has gained a lot of football experience," he said.
"When the team needs him he will give us his strength and his goals."