The Spanish giants will go head-to-head at the Nou Camp on Saturday with Real six points clear at the top of the La Liga standings.
Barca and Sevilla are locked together on 27 points and, having already drawn three and lost two league games this season, the Catalans have failed to replicate the form that saw them lift the Spanish top-flight trophy last term.
Real are yet to be beaten and Pique feels another success for Zinedine Zidane's side may be terminal to Barca's hopes of retaining their title.
"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."
Sevilla face Granada on the same day and will be hopeful of taking another three points against the basement side to keep the pressure on Luis Enrique's men.