Carlo Ancelotti did not travel to London with the rest of the Real Madrid players and staff on Tuesday, ahead of their Champions League quarter-final first leg against Chelsea.
Ancelotti tested positive for coronavirus last week, which forced him to watch Los Blancos beat Celta Vigo 2-1 on Saturday from home.
Real had hoped that Ancelotti would have returned to the touchline to face his former club at Stamford Bridge, but his involvement in the fixture is in doubt.
According to Spanish radio station OndaCero, the Italian has not yet flown to London and will instead take another PCR test on Wednesday morning in the hope of being cleared to travel before that evening's kick off.
It has not been revealed if Ancelotti is suffering from any symptoms with son and assistant manager Davide primed to step into the hot seat if he is unable to make the game.
Real completed a dramatic comeback in the second half of the second leg of their last-16 clash with Paris Saint-Germain to book a quarter-final meeting with Chelsea, and they look in good shape ahead of the tie.
Eden Hazard and Luka Jovic – who have been bit-part players at Santiago Bernabeu this season anyway – are Los Blancos' only notable absentees.
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