South Korea forward Son, 27, will have surgery this week after fracturing his arm during Sunday's 3-2 win at Aston Villa, in which he scored twice.

Tottenham are already without England striker Harry Kane, who tore his hamstring at Southampton in January.

"I'm not going to count on him again this season," said Mourinho.

Earlier on Tuesday, a Spurs statement said Son - who has scored in his past five matches for the club - would be sidelined for "a number of weeks" with the injury.

Mourinho added: "If he plays two or three games then it's because he [Tottenham's press officer] is very optimistic, and I hope he is right. But, in my mind, I'm not thinking about that.

"We are going to miss him. The club wrote a nice statement. If I was the one to write the statement, I would write different."

Son's absence means 27-year-old Brazilian Lucas Moura, 22-year-old Dutchman Steven Bergwijn, signed in January, and Republic of Ireland international Troy Parrott are Tottenham's only fit forwards, though Mourinho believes 18-year-old Parrott "is not ready" to play at senior level.

"The situation couldn't be worse. That is obvious," added the Portuguese. "There is nothing we can do. We are going to play with the players we have available.

"I was worried about not having attacking options on the bench, now I don't have attacking options on the pitch.

"My thoughts are that Troy Parrott is not ready and [19-year-old English winger] Ryan Sessegnon is not a striker.

"No strikers, no market. Nothing. The only help we can have is our crowd, the Tottenham supporters. That is the only thing I ask because to the players I cannot ask more than what they are giving."