West Ham manager Sam Allardyce feels new Financial Fair Play rules in the Barclays Premier League next season could "blow the whole deal" for signing Andy Carroll.
The on-loan Liverpool striker netted his fourth goal in the last five appearances for the Irons in Saturday's 1-1 draw at Southampton.
England forward Carroll, 24, maintains he would have no problems with the transfer being made permanent in the summer, but Allardyce revealed committing to such one marquee signing could just prove too costly.
Premier League clubs last week voted through new regulations which will limit how much of the new television income can be spent on wage bills and there could even be points penalties for severe breaches of the guidelines.
"The hardest thing is the overall package, the overall negotiation which needs to go on to make sure it can be sustainable in terms of what we can do," said Allardyce, whose side host leaders Manchester United on Wednesday night.
"I will still point towards financial restrictions being implemented next season - they could blow the whole deal in one go.
"Financially you are restricted to be able to do it.
"So in one fell swoop the financial restrictions mean Andy Carroll can't sign for us from Liverpool because it's too expensive, even if he wanted to."
Allardyce added: "Somebody will have a bigger budget than us somewhere, but I tell you that is what's going to happen, I might not be able to afford Andy Carroll, full stop, even if I wanted him, even if the chairmen wanted him, even if we all wanted him, which we do, it will not be allowed to happen."
Allardyce believes it will take some time before the true impact of the new regulations, which have been brought in to try to level the playing field in the top flight, can be felt.
"I suppose across the board when you first introduce something new the fair/unfair scenario has to get sorted out somewhere along the line to find out how you have to tweak it to make it better," he said.
"But if we want Andy Carroll, or any player, and you look at the whole thing, you are going to have to move very quickly now because your budget is going to say that (figure) and you are not allowed to go over that apparently, and because you are not allowed to go over that, you have to say (to the player) 'sorry and off you go', so then it is very difficult to improve your side from last season."
West Ham moved onto 38 points at the weekend, and while they are not expected to pull off a shock win over the title-chasing Red Devils tomorrow, Allardyce feels his side have done just about enough to secure another season among the elite.
The Irons boss, however, has some injury problems in defence, with James Tomkins limping off on Saturday.
"Winston Reid, James Tomkins and George McCartney (injured) leaves us a little thin on the ground for selection of defensive players," Allardyce said.
"If none of them make it, Emanuel Pogatetz has to come into the team, and that leaves only young cover there with Danny Potts and Jordan Spence, which is slightly concerning when we have got three games in a week.
"But it is life sometimes that when you have had a particularly good period, injuries then take their toll.
"Instead of the injuries being spread through the team, they are all in one area, which obviously causes us more concern than if it had been one in midfield, one up front and one defensively
"Mark Noble will be close to getting back, but obviously the main concern at the moment is defensive bodies available for Wednesday."