Youssouf Fofana headed the hosts in front in the 19th minute but Raphinha brought Barca level just three minutes later.
The Brazilian, who also had a treble in the midweek 7-2 win over Racing Santander, then put the champions in front early in the second half and, shortly after hitting the post, added a third in the 69th minute to seal it.
Racing were on the wrong end of another heavy scoreline as Celta Vigo recorded their first league win of the season in some style, winning 5-0 as substitute Pablo Duran scored a late brace.
Former Chelsea boss Liam Rosenior sparked a post-match melee as he celebrated Paris FC's 2-1 Ligue 1 win over his old club Strasbourg in front of visiting fans.
Rosenior's side moved up to third in the table thanks to goals from Ilan Kebbal and Pablo Pagis before a late Mamadou Mbow own goal, but players and coaches clashed after Rosenior went to the Strasbourg end and slapped his chest.
Ernest Nuamah's brace helped Lyon to a 4-0 rout of Rennes.
Borussia Dortmund continued their perfect start to the Bundesliga campaign as Maximilian Beier's 70th minute goal earned a 1-0 win at Stuttgart.
Mitchell Weiser struck at the death as Werder Bremen came from 2-0 down to beat Augsburg 3-2 at home.
In Italy, second-placed Inter Milan came from 2-0 down to draw 2-2 away to leaders Roma, who had led through Kouadio Kone's first-half double before Lautaro Martinez twice hit back after the break.
That allowed Lazio to move level on points with the top two as Mattia Zaccagni and Tijjani Noslin scored in a 2-0 win at Venezia.
Mohamed Salah scored his first hat-trick for Trabzonspor, adding an assist, as they stunned Super Lig leaders Galatasaray 4-0.
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