Barcelona head coach Ernesto Valverde was left pondering Ousmane Dembele's red card at the end of his side's rout of Sevilla, claiming the Frenchman's grasp of Spanish would have restricted the words that led to his dismissal.

Dembele was sent off two minutes from time for protesting the red card shown to Barcelona debutant Ronald Araujo in Sunday's 4-0 LaLiga victory, and Valverde said the late disciplinary flurry did not reflect the manner of the game.

Barca cruised to their fourth consecutive win in all competitions, scoring three goals in eight first-half minutes before captain Lionel Messi added a fourth with a second-half free-kick.

Valverde praised his side's incisive forward play after the champions moved within two points of top spot thanks to goals from Luis Suarez, Arturo Vidal, Dembele and Messi.

"We have had more punch than them, there is the key," Valverde told reporters afterwards.

"The result is substantial, but we don't have to be forgiving to our rivals.

"The red cards? It's the referee's decision. Everyone has their opinion. I've seen a pretty clean game.

"It didn't seem like Araujo's fault, but I always see everything in favour of my team.

"I don't know what Dembele may have said to the referee but I don't think it's a long sentence because it's hard to hear him speak Spanish."

Video analyzed after the match seemed to show Dembele calling the referee "muy malo" or "very bad."

Sevilla coach Julen Lopetegui hailed his side's bright start, in which Luuk de Jong squandered three good opportunities to put the visitors ahead.

But Barcelona's dominance thereafter leaves Sevilla with three defeats from their last four LaLiga matches and Lopetegui felt the result at Camp Nou was harsh on his players.

"The first 30 to 35 minutes were ours," said Lopetegui. "We had very clear chances and we didn't score. And in such a scenario when you don't take advantage, the laws of football take effect."