Barca were looking to take advantage of Real Madrid slipping to defeat on Friday night (Saturday AEST) and they did so in style, sending out a strong statement.
Yamal bagged a double and had a third disallowed, with Fermin Lopez, Raphinha and Pedri also on the scoresheet as Hansi Flick's side ran riot.
Sevilla were denied a win at Espanyol as Marcos Fernandez's goal in the eighth minute of added time earned a 1-1 draw.
After Arouna Sangante saw red in the 56th minute, it looked like the visitors were going to steal the win when Lucas Stassin scored in the 85th minute.
But they could not hold on as Fernandez struck at the death.
In Italy, Federico Gatti scored deep into stoppage time as Juventus snatched a late 1-1 draw with AC Milan at the Allianz Stadium.
Both teams had won their games coming into the contest and it looked like Ruben Amorim's Milan would continue their streak when Alphadjo Cisse put the visitors in front in the 69th minute.
Juventus got their deserved equaliser two minutes into stoppage time courtesy of Gatti's header which ensured both teams continued their unbeaten starts to the season.
Lassine Sinayoko's hat-trick earned Paris FC a dramatic 3-2 win against Marseille in Ligue 1.
After opening the scoring in the first minute, he then restored his side's lead 18 minutes later following Amine Gouiri's leveller for the hosts.
Gouiri equalised again eight minutes after the restart, but Sinayoko took home the match ball when he converted an 86th-minute penalty.
In Germany, Augsburg moved top of the Bundesliga after two rounds following a 4-1 win over Eintracht Frankfurt.
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