Moreira, 19, told the club's website: "It was a great feeling after the Arsenal game. I was extremely proud of my performance and it was great to see how much the win meant to the squad and the coaches.
"Before the fixture, I made sure I was in the zone and was completely locked in so I would be able to be mentally prepared to go out and give my all.
"Being mentally ready is crucial especially when heading into these big fixtures. Having control of your mindset will develop your performance and enable you to go out and make a difference."
He also said: "One of my goals showed the importance of remaining alert and focused throughout every second of the game. I picked up a loose ball that came from Tyrique's rebound, so to be reactive and conscious of your surroundings is crucial.
"I was extremely happy with my final finish and getting my first-ever hat-trick. I have been working really hard on perfecting my finishing skills, so it was great to see my work pay off."
The Portugal U21 attacker added: "I love these knockout games as it gives a different type of pressure. It is a one-chance game, so there is no excuse to not give everything.
"I always reflect on my experiences with Portugal. During the international break I was exposed to a large crowd and playing against unfamiliar opponents, therefore it teaches you how to adapt and not be thrown off by change."