Ahead of this weekend's Bernabeu clash, Toshack, who spent over 10 years in Spain as a manager, says that off-field issues relating to star player Neymar have had a negative impact on the club.
"You cannot say that he was unfortunate to arrive at Barcelona, it is a privilege, but things have occurred out of his control and have influenced the general support," the 64-year-old told Cadena SER.
"Any manager feels uncomfortable if they do not win whether in Barca or Benidorm. We live by results and successes, I wish the best for [Martino] but the result could judge his future."
Toshack has been out of management since resigning from his role at Azerbaijani club Khazar Lankaran in November last year.