It didn't take long for the Brazilian star to appreciate the playing riches on show on the pitch.
Three-time defending champion Barcelona will play the first leg against its crosstown rival at Espanyol's RCDE Stadium next week.
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.
Messi netted twice in two minutes inside the opening quarter of an hour, steering home from two Alba crosses, before he returned the favour with a sumptuous pass that allowed the full-back to score his second goal of the season.
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"It's luxury to have Leo in the side; he's the best in history".
"The first half was extraordinary on every level", Valverde said of the game in general.
Sevilla were comfortable 4-1 aggregate winners over Cadiz of La Liga 1|2|3 in the last round but will face a much tougher test against an Atleti side who also had things their own way in the last 16, beating third tier Lleida Esportiu 7-0.
Despite losing 2-1 at Villarreal, who are now sixth in La Liga, Leganes progressed on away goals having won the first leg 1-0.
On Wednesday, Real Madrid laboured to a 2-2 draw with Numancia to progress to the quarterfinals 5-2 on aggregate.
The semifinals of the competition are scheduled for January 31 (first leg) and February 7 (second leg), while the final will be held on April 21.