The 36-year-old reserve goalkeeper has featured in just one previous game for the Catalans this season, but he will replace Victor Valdes between the posts at the Santiago Bernabeu.
"I have decided to play Pinto,” Guardiola explained during his pre-match press conference on Tuesday night.
“He’s a great goalkeeper and I do not think people who know him doubt that.
“We certainly do not and those who have seen him in action these past few years know that he has always played at a very good level.”
There have been suggestions in the media that Barca might adopt a more cautious approach in Madrid, given that they still have the second leg to come at Camp Nou next week.
However, Guardiola insists that the reigning world, European and Spanish champions will play their usual game.
"Being cautious means waiting to see what happens,” he mused. “Therefore, there are endless attacks from Madrid and, ultimately, they will always score a goal.
“The only way to win this tie is to have the ball and implement good positional play to avoid their counterattacks.”
Guardiola also insisted that his side’s 3-1 victory in the Spanish capital last month will not have any bearing on this latest Clasico.
"In sport there are no precedents,” he argued. “Tomorrow is a new day and there will be 90,000 people there to encourage the team in white.
“You have to start over. That's the beauty of the game.”
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