The expensively assembled front three have been in lethal form in recent weeks for the Spanish giants, scoring all 12 of Real's goals between them in the past three matches.
Following their defeat to Barcelona in the Clasico last month, Real have seen Ronaldo score six times, while Benzema and Bale have both found the back of the net on three occasions.
That does not bode well for Sociedad, who have not beaten Saturday's hosts in their last 12 competitive meetings, a run that stretches back to May 2004.
"We have to stay focused and play a good game if we are going to get something," Prieto said ahead of the match.
"Let's see if we can continue in the way that the team is playing on a big stage.
"We always expect a great Real Madrid, playing at home with the support of their fans, and we need our best."
Coach Carlo Ancelotti will have a decision to make about who starts in goal after Iker Casillas' fine performance against Juventus in the UEFA Champions League in midweek, with Diego Lopez having started every league game so far this season.
