The game saw Jules Kounde make his long-awaited debut for the club after his move from Sevilla, having had his registration postponed, but it was another of Barcelona's marquee additions who stole the show.

Poland international Lewandowski struck in both halves of the contest at Camp Nou, a poacher's finish at the far post for his first and a deft back-heel for his second.

Pedri and Sergi Roberto were also on the scoresheet for Xavi's side, which stands unbeaten in LaLiga with seven points from a possible nine.

The host started strong but was foiled by the frame of the goal, Lewandowski heading into the post before Ousmane Dembele smashed a ferocious effort against the crossbar.

A breakthrough came after 24 minutes, though, Lewandowski on hand at the far post to stab home Raphinha's inviting cross.

It was two before the break, Pedri finding space around the penalty spot to comfortably steer Dembele's pass beyond the helpless Jordi Masip.

Barcelona's dominance continued in the second period, boasting 66 per cent possession on the hour mark, and, while fans had to be patient for a third goal to capitalise on its dominance, it was worth the wait.

Dembele cut inside from the right to tee a pass through to Lewandowski, who expertly back-heeled a finish past his marker and the keeper – taking his tally to four goals in three matches for his new side.

Lewandowski was denied a hat-trick in stoppage time, striking the frame of the goal from close range, but Sergi Roberto was on hand to tuck away the rebound.