Antoine Griezmann marked his home league debut for Barcelona with his first competitive goals for the club as Real Betis were well beaten in La Liga.
After the champions were surprisingly beaten 1-0 by Athletic Bilbao in their opening match of the season last week, they rebounded in style on Sunday.
Griezmann, signed in July for £107m, swept in to equalise Nabil Fekir’s opener, then bent in a lovely second five minutes after half-time.
Barcelona coach Ernesto Valverde admitted it had been a big night for the new arrival.
“I have to admit it was a really important day for him given the absentees we had,” Valverde said.
“He responded brilliantly. He dropped deep to help the midfield, but also pushed on and can lose his man brilliantly.
“For us, it’s fundamental to have players who can clock up goals and the fact Griezmann debuted at the Camp Nou and scored is great news.”
Strikes from Carles Perez, Jordi Alba and Arturo Vidal completed a memorable day for the Catalans as they marked defender Gerard Pique’s 500th appearance for the club.
Barca, who were without injured talisman Lionel Messi, started on the back foot and fell behind when Nabil Fekir netted with a sublime angled strike in the 15th minute.
Griezmann, who joined Barca last month from rivals Atletico Madrid, scored four minutes before halftime to level the scores.
The French World Cup winner’s maiden goal for the club proved to be the catalyst for the Spanish champions as they went on to score four more unanswered goals in 27 second-half minutes.
“I was pleased with how we did in the first half, but when you go behind you always think that there’s stuff to change,” Valverde told reporters.
“We needed to score and the goal to make it 1-1 changed things for the better and we might have even scored a second [before halftime]. The game was high tempo and we like it that way.”
The Catalans have three points from two La Liga games, while Real Betis have lost both of them games this season.