The Catalan giants host their great rivals at Camp Nou knowing that they need a win to close the four-point gap on their opponents at the top of La Liga.
|Barcelona & Real Madrid to do battle
"Barcelona will start the Clasico at a fast pace and the pressure will be on Madrid," he told Mundo Deportivo.
"Another defeat would hit them hard, especially after losing in the Champions League semi-finals [to Bayern Munich]."
Rexach, who plied his trade in Catalunya between 1967 and 1981, knows that Pep Guardiola's men can ill-afford a slip-up.
"Barca have only the option, which is to win the match. If Madrid wins or draws the league is over.
"If Barca end up winning the league, however, all the talk will be about Madrid throwing it away," he concluded.
Goal.com will be running a dedicated LIVE! on Saturday from 15.00-23.00BST to bring you all the build-up, action and reaction from Camp Nou for the latest installment of Clasico as Barcelona and Real Madrid fight it out in their hopes to be crowned the 2011-12 Liga champions. Our team of editors will also be on hand to bring you their expert insight while also answering your questions.