Alvarez scored in the 6-0 win in Prague on Tuesday.
He later said, "Great match, lots of goals in our favour. We needed it. We have been doing things very well, we have to keep working, improving things but we have to continue on this path.
"We know that due to the format of the tournament we need to score three points and score goals. It is important to score as many goals as we can.
"When I saw the foul, I told Rodri (De Paul) that I was confident and it was a great goal. I don't know if I'm a specialist, I've taken the shot for City and River, at my previous clubs. It was the first one I was given and it's important to open the scoring and keep scoring goals."
He added: "It was just a matter of time before we all started feeling better. We have to continue on this path to keep growing."