Gerard Pique isn't comfortable with Barcelona's system
Barca take on Juventus in the Champions League tomorrow night before meeting Real at the Bernabeu on Sunday.
But Pique is worried about the defence and admits Luis Enrique’s tactics just aren’t working.
Barca have conceded 50 goals in 51 games this season – including three against Juve in the first leg.
Coming into the crunch week of the Barca season, Pique said: ”We don't feel solid with three or four at the back.
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"We are not at our best in terms of confidence. If you feel solid, everything is different.
"Juventus and the Clasico are closely related. [A comeback] will gather a lot of momentum.
"If not, the Madrid game will be more complicated."
Barca are three points behind Real, who have a game in hand over their title rivals.