"Ashley is an inspiring leader when he is on the pitch," said Houllier.
"I know the captain is Stiliyan when he plays but, when he is not playing, Ashley is a leader because of the efforts he puts in."
He added: "As the game goes on, his efficiency and work-rates goes on as well and does not diminish."
The display of Young, who kept the armband after Petrov declined to take it off him when coming on as a late substitute, will have impressed watching England manager Fabio Capello as the 25-year-old operated in an advanced role between midfield and attack.
Young hoping to catch Capello's eye
"I like him [Young] to play in that position to be fair," said Houllier. "He can be a real specialist.
"He can be a striker and he can also be a link between the midfield and the attack."
Young opened the scoring with a penalty having been fouled by Keith Andrews before Villa winger Marc Albrighton's cross went in off Rovers defender Grant Hanley for the home side's second.
Stewart Downing added to Villa's lead and, despite Nikola Kalinic pulling one back for Blackburn, Young slotted in to
complete a convincing victory
which gave the Midlands side some breathing space from the relegation zone.
"I think some people may have been disappointed with the first half," said Houllier.
"I was not and I told the players to keep their heads up, keep believing in what we were doing.
"We had to put more tempo, which we did in the second half. I said keep passing and moving once we get in the final third and eventually we would find a solution and that paid off.
"More than the result, was the quality of the play. We made some mistakes but I want the team to play that way with confidence and to me, it has got to be entertaining."
Houllier also reserved praise for veteran midfielder Robert Pires as he played his first game since the
FA Cup win over Blackburn
on 29 January.
"The game Robert played against Blackburn in the FA Cup gave him match fitness and confidence," said the Villa boss.
"In training he has been good, nearly scoring and making goals, so I thought he would bring something.
"It was his best game for Villa. He was more confident at taking the ball."
Source: BBC Sport
Source: BBC Sport