The Welshman believes los Blancos are the clear favourites for Sunday's encounter at the Santiago Bernabeu as he believes the Blaugrana cycle of success is nearing its end
The Santiago Bernabeu side currently hold a four-point lead over their arch-rivals and Toshack is confident the Catalans will be out of the Liga title race after Sunday's encounter.
"Barcelona will need all the luck in the world to beat Madrid and if they do, it will be a massive surprise," the Welshman told Cadena SER.
"After this weekend, Madrid will hold a seven-point advantage over Barca. I could be wrong, but that’s what I sense happening.
"There’s a lot of pride at stake in these matches; I haven’t got any personal interest but I can sense that Barca are having a few problems."
Toshack then went on to say that he feels Barcelona's cycle has come to an end and expects a difficult period for the Catalans.
"It could be that they are approaching the end of an era, I can see some signs of resignation," the former Liverpool forward opined.
"The players’ body language when they’re out on the pitch says a lot about the situation.
"They have done remarkably well for several years but problems keep arising. A long cold winter is coming their way and they need a radical change."