That performance was widely seen as the finest in world football last season and set the template for what was to follow, Barca being crowned Spanish champions for a third successive season and winning the European Cup for the second time in three years.
There has been a shift since the Catalans destroyed Jose Mourinho's side. It started in April when Los Blancos won the Spanish Cup against Barca in Valencia. It has continued, with Real still improving and Barca less than their usual spectacular selves.
This swing is now tangible. Six points. That was the difference between the giants after both played their 13th league games of the season at the weekend.
Real, the league leaders, came from behind to beat their neighbours Atletico at home 4-1. That much was expected, for Atletico have not won a Madrid derby since 1999.
The surprise came not in the centre of Spain's capital, but a down-at-heel satellite city 20 kilometres to the south. Getafe, the top flight's worst supported club, with average home crowds of just 8,600, stunned Spanish football by beating Barca 1-0.
Despite their endeavours in overcoming AC Milan away midweek, Pep Guardiola's side dominated in Getafe, enjoying 73 per cent of possession. They had 29 shots to Getafe's eight. They could not find a breakthrough, though, and just as most Barca fans were beginning to think that their side had dropped two points, Getafe, whose 4-2-3-1 formation had effectively become 6-3-1, scored from a corner to inflict Barca's first league defeat of the season.
Real have never enjoyed more than a three-point advantage over the Catalans since Guardiola took charge in 2008. Now they have double that. Win at the Bernabeu on December 10 and that could become nine, depending what happens this weekend.
Real are strong, purposeful and confident. It is hard to see them dropping any points as they go in search of their first title since 2008, but Barca are far from finished. Indeed people were saying exactly the same thing a year ago … before Barcelona silenced them by putting five past Real.