Following is an analysis with five main reasons for their success.
CLOCKWORK CONSISTENCY
Barcelona's well-oiled machine, built around the midfield trio of Spanish internationals Xavi, Andres Iniesta and Sergio Busquets, has continued its unrivalled domination of possession, frustrating rivals forced to chase the ball for long periods.
Pep Guardiola's outstanding achievement has been to maintain the hunger for success in a squad that has already won every available trophy.
His decision to off-load striker Zlatan Ibrahimovic in favour of Spain's David Villa has been vindicated and it led to a tighter squad unit without any of the controversy that dogged last season.
He conducted the campaign with a first-team squad of only 18 outfield players, adding Ibrahim Afellay in January, exploiting the versatility of players such as Javier Mascherano and Sergio Busquets to cover at centre-back after Eric Abidal's surgery on a liver tumour.
The former Barca midfielder refused to rise to Real Madrid coach Jose Mourinho's constant sniping, until his uncharacteristic outburst on the eve of the Champions League semi-final when the bad blood between the clubs boiled over.
MESSI'S GOALS
The tirelessly enthusiastic 23-year-old has avoided any serious injuries and once again has shown an unerring ability to score important goals. The team's domination of possession combined with Messi's more central role means he sees plenty of the ball and he has also weighed in with 19 assists, more than any other player in La Liga.
Messi's inability to exercise the same influence for Argentina speaks volumes for the way his Barca team mates play to his strengths.
