Real had dropped points for the first time this season earlier in the evening at home to Villarreal and must have feared reigning champions Barcelona would cut their lead to one point when Ivan Rakitic headed home an inviting Andres Iniesta cross in the 41st minute.
But Diego Simeone's men were dogged opponents and got the equaliser their efforts deserved when substitute Angel Correa got the better of Javier Mascherano to score after an hour's play.
There was also the concerning sight of Lionel Messi and Sergio Busquets limping off with second-half injuries for coach Luis Enrique, and it remains to be seen whether he will be without the influential duo for a prolonged period.
Barca coach Luis Enrique said: “We knew it wouldn't be an easy game, that we'd have to attack a team who sat back, who work hard, leave few spaces and make things tough.
“We had a good first half, without creating many chances. We attacked really well and they defended amazingly.
“We had chances when we got into our rhythm, but we know and accept that there are things we have to improve."