Madrid are flying high atop La Liga, six points clear of their rivals ahead of Saturday's encounter at Camp Nou.
Luis Enrique's men have stuttered in the start of their title defence this term, and were held to a 1-1 draw against Real Sociedad on Sunday.
And the need to make up for lost ground makes the clash crucial for Barcelona, who have now drawn consecutive games, according to Pique.
"It is more important for us than them," he said to Mundo Deportivo. "Because if they won, they would go nine points clear and it would be difficult."
Barca needed a second-half goal from Lionel Messi to earn a point at Anoeta at the weekend and were fortunate to have emerged with a point.
But Pique played down the significance of the result, saying: "Yesterday was not a great day.
"Things did not go quite right. It was a point that is now not so bad.
"After showering and reflecting, I think if we win on Saturday things will be different."