An own goal by Lucas gave Villa the lead before Curtis Davies and an Ashley young penalty sealed victory at Anfield, with Fernando Torres scoring for the Reds.
However, before praising his players, O'Neill revealed his continued discontent with the behaviour of some of the club's fans at such an early stage of the season.
"It was all after 45 minutes of competitive play since we finished sixth in the league," added O'Neill. "This is a daunting league. Teams have improved and they have spent money and it's going to be exceptionally difficult."
Of the victory at Anfield, O'Neill stated: "I have quality players and this was a terrific win. I was absolutely thrilled - we put in a big effort in the match.
"We are capable of scoring goals and we did that. We were much fitter tonight and it was a great performance - in terms of effort and ability. What it says about the season? Who knows, it's too early."
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