It didn't take long for the Brazilian star to appreciate the playing riches on show on the pitch.
"The first half was extraordinary", Barca coach Ernesto Valverde said.
Just one minute later, the Blaugrana were ahead thanks to Lionel Messi, who was on hand to rifle Jordi Alba's cross towards goal, the ball powering through the hands of Celta goalkeeper Sergio Alvarez.
Earlier in the day Espanyol overturned a 2-1 first leg deficit against Levante to qualify 3-2 on aggregate thanks to a 2-0 win in Levante's Ciudad de Valencia Stadium.
"It's a luxury to have him in the team", Alba told Gol Television.
Scientists discover rare 200 million-year-old butterfly fossils
As per the study, the only moths and butterflies having hollow scales are from the Group Glossata which are known to have proboscis.
Barca did make it a five-star performance, though, as Rakitic took advantage of some woeful Celta defending to head home from a corner three minutes from time.
Two derbies feature in the Copa del Rey quarterfinals, with Barcelona facing Espanyol and Real Madrid taking on Leganes. "We always look for each other to score goals and today we have done it twice", Alba said.
Sevilla beat Cadiz 2-1 with goals from Wissam Ben Yedder and Joaquin Correa to advance 4-1 on aggregate.
Zinedine Zidane's Real laboured to a 2-2 draw with Numancia on Wednesday to progress to the quarter-finals 5-2 on aggregate.
Celta had drawn 2-2 at Barcelona in La Liga last month and had gone into Thursday's match after holding Madrid to a 2-2 draw in the league last weekend.
The first legs of the quarter-finals will take place on Wednesday and Thursday next week, with the return legs scheduled for a week later on January 24 and January 25.