The Guinea-born midfielder saw 74 minutes of action as Ronald Koeman's men progressed to the next round of the competition after extra-time
Ilaix Moriba said he could not sleep before making his Barcelona debut in their 2-0 victory over Cornella in Thursday’s Copa del Rey encounter.
The 18-year-old was handed a spot in the Blaugrana's starting XI and he played for 74 minutes before he was replaced by Sergio Busquets.
Ilaix gave a good account of himself in the middle of the park as goals from Ousmane Dembele and Martin Braithwaite in extra-time secured Barca's passage to the Round of the 16.
Although he has been a dominant fixture for the Barcelona B side, the Guinea descent first made Ronald Koeman's matchday squad on January 9 but he was an unused substitute in their 4-0 La Liga win over Granada.
After Thursday’s memorable outing in Cornella, he described his emotions and his readiness to take each opportunity step by step.
“It’s an amazing feeling. Since the coach told me I was going to be in the side today it’s been good. I got home and I couldn’t sleep,” Ilaix told Sport.
“I am really happy at the club, especially with the coach, very grateful, and also with all my teammates who made it possible for me to play well.
“I just take it day by day. It’s the club who tell me up [first team] or down [B team]. I have to do my own thing and be aware that I am a B team player, with Pimi, who I am very grateful to, also to Catena, Franc, Marc Serra.”
Ilaix turned 18 on Tuesday and he described his appearance at the Campo Nuevo Municipal de Cornella as the perfect birthday gift.
He added: “This is the best present I could have and I am so grateful to Koeman."
He has played for Spain U17 and U18 teams but he is still eligible to play for his country of birth - Guinea or his father's country, Liberia - on the international scene.