Sheffield United's compensation claim over the Carlos Tevez affair looks set to be delayed until next year as West Ham step up their legal fight.
The Blades are claiming £30million in damages for being relegated from the Premier League after winning an arbitration tribunal ruling last month.
West Ham are due to submit a claim to the Court of Arbitration for Sport (CAS) in Lausanne tomorrow, asking them to rule on the case, and are also considering High Court action.
Meanwhile, Lord Griffiths, the 85-year-old law lord who headed the arbitration panel, is due to make a directions hearing tomorrow laying out the timetable to decide compensation, but West Ham are likely to ask for a postponement.
It now looks as though it will be February next year before any compensation decision is reached, and even longer if the case goes to CAS or the High Court.
If Sheffield United do not give the go-ahead for CAS to arbitrate in the case, however - and there has been no sign of that so far - then that hugely decreases the chances of that court agreeing to take the case.
A West Ham spokesman called on the Blades to agree to take the case to CAS.
The spokesman told PA Sport: "We do believe that the arbitration panel's ruling needs to be reviewed by a court which can help resolve the outstanding issues in this case.
"This is not about the issue of damages - the current ruling has major implications for English football.
"West Ham will continue to look at the available options for further action and we do believe that Sheffield United should join us in a hearing at the Court of Arbitration.''
Sheffield United lost two independent appeals against the Premier League and a High Court action before winning the independent arbitration ruling brought under FA rules.
West Ham have sacked the legal team that represented them at the arbitration panel and have brought in a new team headed by Maurice Watkins, the solicitor who is Manchester United's legal adviser.
Sheffield United's chairman Kevin McCabe refused to comment on West Ham's call beyond saying: "If that is what they are saying, then that's their prerogative. We will not be commenting.''