David Villa scored in his first competitive appearance since 2011 and Lionel Messi netted a brace as Barcelona claimed a convincing victory over Real Sociedad in new coach Tito Vilanova's Primera Division debut in the Nou Camp hotseat .
Villa, who missed the second half of last season and Euro 2012 after breaking his leg in December, netted after appearing as a late substitute to complete the win as Barca showed it was business as usual despite this summer's departure of record-breaking coach Pep Guardiola.
Earlier, during a frenetic start which saw four goals scored in the opening 16 minutes, Barca charged into a 3-1 lead with Carles Puyol - who also missed Spain's triumphant Euro 2012 campaign through injury - notching the first.
Sociedad briefly drew level when Gonzalo Castro netted but Messi then struck twice in five minutes to put the home side two goals clear.
Pedro Rodriguez then added a fourth before the break before Villa climbed off the bench to also get his name on the scoresheet as Vilanova's men made an impressive start to their Primera Division campaign.
Perhaps boosted by Real Madrid's 1-1 home draw with Valencia earlier in the evening, Barca - who saw their three-year reign as Spanish champions ended by Jose Mourinho's side last season - came flying out of the blocks and needed just four minutes to take the lead when Puyol powerfully headed home Xavi's corner.
That was the ideal start for Barca but they were lucky to still be ahead 60 seconds later as Sociedad forward Antoine Griezmann narrowly missed turning in a cross at full stretch.
However, Barca failed to heed that warning as five minutes later the visitors drew level as Castro latched onto a Asier Illarramendi through-ball before beating Victor Valdes with a rising shot at his near post.
Any chance of a Sociedad upset was banished within seven minutes, though, as Barca star Messi worked his magic.
The Argentina ace, who scored an astonishing 73 goals last season, put the hosts back in front with a shot from inside the area and he made it 3-1 with a close-range finish after his initial effort had been deflected out to Cristian Tello on the left, with the winger bundling a cross back into the danger area.
Messi was denied a hat-trick by the feet of visiting goalkeeper Claudio Bravo in the 36th minute before Griezmann tried his luck with an audacious long-range lob that the back-peddling Valdes tipped over.
If that had gone in it could have put a different complexion on the match, but the contest was put to bed four minutes later when Pedro made it 4-1 with a half-volley at the far post following another Tello cross.
There was just one more goal after the break, but it was a notable one as Villa's name finally appeared on the scoresheet after an absence of eight months.
Spain's record goalscorer replaced Pedro in the 75th minute for his first competitive appearance since suffering his injury, and within nine minutes of his arrival he found the back of the net with a perfect left-footed finish from Andres Iniesta's cut-back.