"I was delighted with Scott because it's always good to come to a new club and record a clean sheet in your first game," O'Neill told Villa's website. "I think he was obviously nervous before the game and that was understandable because he'll want to do well for Villa.
"Last season he was voted Charlton's Player of the Season but this is a new campaign now and he's eager to do even better this term.
"He came in on the back of Stuart Taylor playing very well the week before against Liverpool and that's never easy. It was a difficult decision for me to make but Scott came in and I thought he played very well in the game."