Bent instantly repaid a slice of his £18million price tag with the first-half winner against Roberto Mancini's side.
It was a huge dent to City's Barclays Premier League title hopes and lifted Villa clear of the relegation zone.
Houllier explained afterwards: "The finish was that of a natural-born finisher, something you cannot teach somebody. That is what he is here for, to score goals.
"Roberto Mancini told me before the game that I'd signed a great player and that is a tremendous start for him."
Source: PA
Source: PA