- João Félix (25')
- Robert Lewandowski (32')
- Ferran Torres (62')
- Raphinha (66')
- João Cancelo (81')
The pair of Portugal internationals made their debuts last round for Barcelona as substitutes two days after they joined the defending champions on loan just hours before the summer transfer window closed.
Félix scored in the 25th minute and then cleverly let a pass run between his legs in the area that Robert Lewandowski fired home to double the lead in the 32nd.
Ferran Torres, who also made his first start of the season, added a third goal in the 62nd when he sent a free kick curling around the edge of the defensive wall and beyond the reach of goalkeeper Rui Silva.
It was the first free-kick goal for Barcelona since Lionel Messi found the net in May 2021.
Raphinha, after going on to replace Torres, scored from just outside the area in the 66th. Cancelo topped the victory in the 81st with a great solo effort after he cut back twice to ditch his marker and beat Silva from an angle.
Barcelona moved top of the league, one point ahead of Real Madrid, who play Real Sociedad on Sunday.
"It was not the perfect game, there are things to improve, but it was an excellent performance. I am satisfied with how the players played with joy and enjoyed themselves," Barcelona coach Xavi Hernandez, whose side face Antwerp in their Champions League opener on Tuesday, said.
"Today it really seemed like we were at Camp Nou. I am happy. The feelings are good. We were exceptional in many moments. This is the path to follow."
Félix moved to Barcelona in a bid to relaunch a promising career that had stalled after the 23-year-old fell out with Atletico Madrid coach Diego Simeone and failed to impress on a loan deal at Chelsea last season.
His goal came after Cancelo recovered the ball and Oriol Romeu met his run into the box with a lobbed pass. Félix missed on his first effort to strike the ball, but he was quick enough to dribble around Silva and thread in a shot from a narrow angle.
Torres, who had to fight for playing time last season and was dropped from Spain's national team after the World Cup, has enjoyed quite a turnaround .
The forward leads Barcelona, along with Lewandowksi, with three goals this season and scored twice for Spain on Tuesday in his return to the national team.
Information from ESPN's Sam Marsden was used in this report.
- José María Sánchez Martínez