Barcelona's Poland striker Robert Lewandowski scored his first goal for the club in a friendly debut at the Camp Nou, helping the La Liga side thrash Mexico's Pumas UNAM 6-0 in the final of their annual pre-season tournament.

Lewandowski, who had failed to score in any of Barca's friendlies on their US tour, opened the scoring on Sunday in the third minute of the Joan Gamper Trophy match after he converted Pedri's pass with a brilliant finish from a tight angle.

Barca's new signing then returned the favour as he set up the 19-year-old midfielder to score two minutes later.

Lewandowski handed Pedri another assist for the Spain international to make it 4-0 in the 19th minute after forward Ousmane Dembele scored their third of the night.

Striker Pierre-Emerick Aubameyang and midfielder Frenkie de Jong got on the scoresheet in the second half.

"I am happy to (have) played the first game at Camp Nou and ... to win the trophy," Lewandowski said in a video on Barca's social media account, holding his Man of the Match award.

The 33-year-old is expected to make his La Liga debut on August 13 when Barcelona host Rayo Vallecano.