Marco Asensio struck twice as Villa won the fifth round tie 2-0.
Riza said afterwards: "I spoke to the lads today, the shift we put in out of possesion, the amount of work we put in to contain Villa, who are a very good side and have a lot of attacking threats.
"Then to be able to keep the ball at times and show moments of composure. I think that was pleasing on our builds and restarts. I thought we showed good composure and moved and manipulated them well.
"Just those final moments where they got the two goals, it was telling bits of magic from them. We're now heading into the league where a lot of our focus is and we can take this performance into that.
"He's had to be really patient. Jak's (Alnwick) been playing a lot this season and Ethan's (Horvath) had to be really patient and he's worked really hard, showed great character and attitude constantly.
"His opportunity came around last week and his performance today was superb some of the saves he pulled off. The quality with his feet playing around the back, so really pleased for him. Really important player for us moving forward in the league.
"The momentum in the cup and the competiton keeps the momentum going and we've been picking up some quite good results in the league anyway and getting ourselves in a position we want to be, so we just need to continue that and get everyone back ready, fit for Tuesday."