The 18-year-old came off the bench to score the sixth of seven second-half goals at the Etihad last night as City progressed into the fourth round in ruthless fashion.
Now, the Spain Under-18 international is hopeful that his debut goal can help him kick on and earn further opportunities under manager Manuel Pellegrini.
"It is a dream to make my debut and also score. I am very happy," he told Sky Sports News. "Last year was very difficult because I played only five or six games before my injury.
"This season I'm working very hard. I know I am an Under-21 player but I have an opportunity and I'll try to do my best.
"I have been working with the first team for two weeks. I didn't expect anything. I was just working, waiting for my opportunity."
The reigning Capital One Cup holders face Newcastle United in the next round.