Madrid's lead atop La Liga was erased as title-holders Barcelona stunned the hosts 3-2 in a thrilling top-of-the-table clash at the Santiago Bernabeu on Sunday.
Lionel Messi scored in the 92nd minute — his second of the match — to silence Madrid and their fans in the Spanish capital after substitute James Rodriguez had equalised seven minutes earlier following Sergio Ramos' red card in the second half.
With the result, Barca and Madrid moved level on points, though the latter have a game in hand in their pursuit of a first La Liga title since 2012, and Marcelo was in a positive mood post-match.
"Everyone expects a lot of things from El Clasico. We've done everything we could to win and even draw with a player less, but we conceded a goal at the end," Marcelo said.
"We did a great job and we go away with our heads held high. We're well placed in two competitions and we'll keep working as we were before. This defeat does not make us inferior.
"In the end, some mistakes and small details have made the difference, not just the counter-attack. I don't give my opinion on referees, although a sending off affects a team because it leaves you with one less player.
"We don't get carried away when we win and we won't get down after a defeat."