The Court of Arbitration for Sport (CAS) have opened proceedings to determine if they can hear West Ham's appeal against a ruling which could see them pay out millions over the Carlos Tevez affair.
CAS confirmed this afternoon that a "statement of appeal" had been filed by Hammers, asking the Lausanne court to adjudicate on an independent tribunal's assertion that they should pay compensation to Sheffield United for their relegation from the Premier League in 2006/07.
A statement from CAS read: "The CAS has initiated an arbitration procedure and will first examine its jurisdiction as a preliminary issue after both clubs have had the opportunity to file written submissions on this point.
"For the moment, no decision has been made with respect to the holding of a hearing. In any event, a decision on jurisdiction is not to be expected before the end of November 2008."
The independent tribunal, convened under Football Association rules last month, found West Ham won at least three points due to Argentina striker Tevez - whose registration with the London club was ruled to have breached Premier League rules on third-party ownership in April 2007.
The tribunal ruled Sheffield United were due compensation, which has yet to be determined but could amount to £50m.
FA regulations which brought about the arbitration hearing also state that no appeal is permitted to a court of law. But in their legal submission to CAS, West Ham are thought to have argued that English football's governing body would be in breach of Fifa statutes if they did not allow for an appeal to the Swiss-based court.
Sheffield United are disputing whether CAS have jurisdiction, and the court have now set about deciding either way.
In their argument against an appeal, the Blades have pointed to the dispute between Ashley Cole and the Premier League in 2005 - where CAS said they did not have jurisdiction to hear an appeal from the player over his £75,000 fine imposed by the league for holding unauthorised talks with Chelsea while he was still at Arsenal.