Former Celtic captain and manager Billy McNeill has accused the club's board of starving Martin O'Neill of the cash he needs to make the Hoops a force in Europe.
The Parkhead legend fears O'Neill will simply walk out of the Glasgow side if this does not change.
Just 18 months after reaching the UEFA Cup final, the Hoops now find themselves out of Europe before Christmas.
McNeill insisted he had suffered the same fate, as had Jock Stein, the man who led them to glory in the 1967 European Cup final.
He told the Scottish Sun: "Martin O'Neill is now in the same position every Celtic manager has faced at some time.
"The club will not finance the ambitions of the manager. I know exactly how Martin must feel.
"His problem is that the money men only look strictly at the finances. They don't realise if a manager is forced to take chances on signing players who are not from the very top strata it rarely works.
"There is no way you can get in with the big boys in Europe without buying good players."
O'Neill was allowed to spend £6million on both Chris Sutton and then John Hartson at the beginning of his reign but has subsequently been only allowed to make more modest purchases.
Steve Guppy, Momo Sylla, David Fernandez, Ulrik Laursen and Stephen Pearson have all found themselves remaining nothing but fringe players.
And the same has already happened to World Cup winner Juninho, who began on the bench against AC Milan on Tuesday.
The Brazilian admitted afterwards O'Neill had lost faith in him just weeks since leaving Middlesbrough.
