Harry Redknapp believes it will take £150million for any Barclays Premier League side to shatter the big four's dominance of the division.
Redknapp has echoed Kevin Keegan's comments that the league is in danger of becoming boring if Manchester United, Chelsea, Arsenal and Liverpool continue to pull away financially.
The Portsmouth manager claims any club outside that elite group need to invest huge amounts of cash to have any chance of reaching the Champion's League.
But Redknapp has warned that still does not come with any guarantees after pointing to the example of Tottenham, who have shelled out around £75million over the last two seasons but find themselves languishing in 11th place.
Pompey owner Alexandre Gaydamak allowed Redknapp to spend £40million over the past two transfer windows on expensive talent such as Jermain Defoe, Sulley Muntari and Glen Johnson but the south coast side still stand 16 points behind fourth-placed Liverpool.
Redknapp said: 'You would need £150million to spend to have any chance of breaking into that top four.
'Look at Liverpool last summer, they spent £28million on Fernando Torres and he is a fantastic player but who else can compete with that?
'I agree with Kevin Keegan, I do not see any way that anyone else can break into the top four.
'Tottenham came closest for a few seasons but if you look at them now they have fallen back into mid-table. Nothing is guaranteed by spending money and it is getting harder and harder to get there.'
Redknapp believes the only solution is for more foreign-based owners to invest significant funds to get clubs on a level playing field with the big guns.
However, that can lead to unrealistic expectations being placed on managers as witnessed by Thaksin Shinawatra's impatience with Sven-Goran Eriksson at Manchester City.
Redknapp, speaking at the launch of Pompey's new club crest and away shirt on board HMS Ark Royal, added: 'I can see more and more foreign investment coming into the Premier League because everybody wants to be associated with it.
'I can see American and Russian billionaires coming in but the trouble is they all want to be winners and only one can win the title. Billionaires do not accept being losers.
'If someone had put £200million into Derby this season then they could have been a successful side and that is the sort of money that will happen in the Premier League.'