Houllier felt Villa reached rock bottom when beaten 4-0 by City at Eastlands in late December.
But it proved to be a turning point and since then Villa have lost only twice in 11 matches in all competitions - and defeated City 1-0 in the return clash at Villa Park.
Keeping his promises: Houllier will be hoping he can guide his side to silverware
Houllier would like to follow on from the Carling Cup success of Birmingham and bring more silverware to the second city.
But he insists that is not his main driving force in the quest for glory.
He said: 'I'm pleased for Alex McLeish (Birmingham manager) because he is a good man, I've known him for a long time and well done to them.
'It has been their year in the cup. If we could win the FA Cup that would be fantastic because it would mean two cups in the same city.
'We will win things, I know that for sure.
'It is not the fact our rivals have won something that is going to change my mind about what we are doing here.
'The FA Cup is an opportunity, although it is not the easiest of the games against Man City.
'But I have got the squad now, playerswho know what we want to do. Whoever plays, I'll be happy and I knowwe've got a good chance.'
How it's done: City rivals Birmingham have clinched the first silverware of the season
Houllier added: 'Last time we went there, it was probably our poorest performance of the season.
'Ever since we have done better and we then beat them at our place.
'They were probably the better side but we won and, so many times, I thought we'd been the better side and lost.
'I still think that was a tremendous win for us because after that we build up a good series of results."We work harder, we run more, we are starting to improve and progress and the fans are enjoying it.'
Desperate for a trophy: Manchester City boss Mancini (left) has Houllier's backing
Houllier is backing City to secure a Champions League spot this season.
He said: 'Roberto's team is improving, and they missed by a whisker the Champions League last season.
'But I am confident they will get it this season.'
Full-back Nathan Baker has been ruled out with the 19-year-old still suffering from concussion after a collision with Blackburn keeper Paul Robinson on Saturday.
Fabian Delph, who replaced Baker, may again deputise as Ciaran Clark will be required to play at centre-back with Carlos Cuellar (hamstring) and James Collins (calf) still ruled out.
Midfielder Jean Makoun is again suspended after his red card against Blackpool at Bloomfield Road.The winners of tomorrow's tie will be at home to either Everton or Reading in the quarter-finals.
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?Explore more:People: Fabian Delph, Paul Robinson, Carlos Cuellar, Alex McLeish, Gerard Houllier Places: Birmingham
Source: Daily Mail
Source: Daily Mail