Randy Lerner's right-hand man and Aston Villa director General Charles Krulak has told Martin O'Neill: "No one is bigger than the club."
Krulak is adamant that O'Neill received full financial backing from Lerner during his four-year spell at Villa.
But he claimed the former Celtic boss was "unwilling" to come to terms with helping Villa to become more stable financially.
Krulak told the Villa fansite VillaTalk.com: "There is absolutely no question that Martin did a good job for Villa and I have said that over and over.
"At the same time, I can promise everyone that he knew and understood the long-range plans for the club and bought into them.
"He knew full well about the need to bring wages in line with revenue - the same as every Premiership club.
"He was absolutely supported by the owner during his time with the club. All one needs to do is look at the money spent.
"The reality is that the wage-to-revenue issue was not addressed and Martin apparently was unwilling to help address it. He quit.
"No one person is bigger than our club - not me, not Randy, not Paul Faulkner (chief executive), not Martin.
"What is interesting is that, apparently, only three of those named understand that fact."
Krulak insists Lerner will not be rushed into finding a replacement for O'Neill.
But he pledged that Lerner will be making public his thoughts on events during the last 48 hours and the future.
He said: "What I will say is that we recognise this is an important decision and one that needs to be done rather quickly but, equally important, in a manner that gets the right man.
"We do know how important this will be. No-one is thinking it will be easy.
"The reality is that we have four days before our first game and rushing out to get a manager is not the smart thing to do just to have someone on the sidelines."
Krulak added: "One of the sad things about this whole affair is that Martin left when he did.
"I agree that the club needs to come out with a statement - and they will.
"Likewise, Randy will have something to say."
Lerner has launched the process of drawing up a list of potential candidates after O'Neill ended his four-year reign yesterday.
Sources close to the American multi-millionaire indicate he would like any successor in place for Villa's second Barclays Premier League clash of the campaign at Newcastle on August 22.
Reserve coach Kevin MacDonald will be in charge for the league opener at home to West Ham on Saturday.
The former Liverpool midfielder could also be at the helm for next Thursday's Europa League tie at Rapid Vienna if the new manager is still not in place.
Former England coach Sven-Goran Eriksson has made it known he would be keen to step into the Villa Park hotseat.
The Swede is known to be eager to return to work after his spell as Ivory Coast coach during the World Cup.
Four years ago Eriksson indicated he would be ready to take over at Villa when the victim of a 'fake sheikh' sting by a Sunday tabloid.
A source close to the former Manchester City boss said: "Of course Sven would be interested in the Villa job. He is keen to return to the Premier League."
Eriksson's agent Athole Still said: "There has been no contact from Aston Villa. Sven gets associated with a lot of big jobs."
United States coach Bob Bradley, Ajax coach Martin Jol and Germany legend Jurgen Klinsmann are all featuring highly in the bookmakers' odds to replace O'Neill.
Chief executive Faulkner met with the club's players not on international duty at Bodymoor Heath on Tuesday.
He explained the events of the last 24 hours and the immediate plans for the future.
But midfielder James Milner - a key figure in O'Neill's decision to step down - was not present as he is part of the England squad preparing for Wednesday's game with Hungary at Wembley.
Lerner's predecessor Doug Ellis, who appointed O'Neill as manager, is confident the current regime will find an ideal replacement.
Ellis said: "I'm saddened and most supporters will be saddened (at O'Neill leaving).
"But the club is bigger than any one man and, in Randy Lerner, Aston Villa have a good chairman.
"I know he will find a successor and I hope all supporters will back him and Paul Faulkner in finding the best possible man for the job."
