Maurizio Sarri says there is nobody in the world who can replace Cristiano Ronaldo, with the Juventus star having flown home after his mother was taken ill.
Dolores Aveiro, 65, was hospitalised in Madeira after suffering a suspected stroke on Tuesday morning.
She is now reported to be in a conscious and stable condition but will be kept under observation at the Dr Nelio Mendonca Hospital.
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Ronaldo flew back to Portugal on a private jet having been granted compassionate leave by the Serie A champions.
"I don’t know what will happen, it is a personal matter, so he will discuss it when he returns,” Sarri told a press conference.