Villa defeated Cardiff 2-0 on Friday night thanks to a brace from Marco Asensio.
Emery said afterwards: "The players performed fantastic. At home with our football we are comfortable. We respected the opponent.
"We were creating chances but not clinical. The second half was still difficult to beat them. We scored one goal. After that it was more easy to dominate and try to score a second goal to finish the match.
"We have our experiences last year in Europe. Today playing against a Championship team, being better than them, trying to respect them because you can lose a match even if you're better than the opponent.
"Numbers for the team and for him (Asensio) as well. We need him. We need Rashford. We need the players who joined in the last window. We need the players coming back from injury. Every player will be necessary for the matches in the next weeks and months.
"Now we focus on the Champions League. We are there and we have to enjoy it and compete. We are going to play Brentford next week. It's a tough week but excited for us and supporters.
"We are not considered favourites to win this trophy. We are contenders but not favourites."