An independent tribunal has ruled against West Ham over the Carlos Tevez affair, says Sheffield United chairman Kevin McCabe.
United claim Tevez was not eligible to play at the end of the 2006/7 season, yet played a key role in West Ham's Premiership survival at their expense.
The club is claiming more than £30m in compensation from West Ham.
Another tribunal will decide on the amount of compensation to be paid at a later date, which is yet to be set.
West Ham were found guilty of breaching Premier League regulations in the signing of Argentine duo Tevez and Javier Mascherano in 2006.
A three-man Premier League arbitration panel fined the Hammers £5.5m, but did not dock them points, and they went on to survive the drop on the final day, while Sheffield United were relegated.
We need to digest the full findings of the arbitration panel and will consult our lawyers on the next steps we might take before making any further comment
West Ham spokesman
Having failed in their attempt to have the original punishment overturned, the Yorkshire club invoked a Football Association rule that allows clubs with a legal dispute to go before an independent tribunal.
McCabe told his club's official website: "I can confirm that both clubs have been notified of the ruling. The arbitration panel has awarded in our favour.
"The matter is still legally in process so I do not wish to comment any further until we have completed that process."
A club statement added: "The Blades began their legal fight for reinstatement some 16 months which also included an arbitration hearing against the Premier League.
"This award could now pose a question as to what the Premier League will do."
Sheffield United's claim was considered by former MCC president Lord Griffiths, Sir Anthony Colman, a former High Court judge, and Robert Englehart QC.
A West Ham spokesman told BBC Sport: "We need to digest the full findings of the arbitration panel and will consult our lawyers on the next steps we might take before making any further comment.
"It would not be appropriate to comment further at this stage."
BBC Sport understands that the Hammers are considering an appeal and could decide to take the case to the Court of Arbitration for Sport in Lausanne, Switzerland.
Tevez and Mascherano were brought to Upton Park from Brazilian club Corinthians on the final day of the 2006 summer transfer window.
The pair were judged to have been partially-owned by Kia Joorabchian's Media Sports Investment (MSI) company.
They have subsequently moved on to Manchester United and Liverpool respectively.
With nine matches remaining in the 2006/07 season, West Ham were rooted to the bottom of the Premier League and 10 points adrift of safety, while Sheffield United were two places above the drop zone.
Tevez scored five goals after this, including the winner against Manchester United at Old Trafford on the final day of the season, to secure West Ham's survival.
Wasn't expecting this to be honest. Will this ruling hold up or will this not be the end?
United claim Tevez was not eligible to play at the end of the 2006/7 season, yet played a key role in West Ham's Premiership survival at their expense.
The club is claiming more than £30m in compensation from West Ham.
Another tribunal will decide on the amount of compensation to be paid at a later date, which is yet to be set.
West Ham were found guilty of breaching Premier League regulations in the signing of Argentine duo Tevez and Javier Mascherano in 2006.
A three-man Premier League arbitration panel fined the Hammers £5.5m, but did not dock them points, and they went on to survive the drop on the final day, while Sheffield United were relegated.
We need to digest the full findings of the arbitration panel and will consult our lawyers on the next steps we might take before making any further comment
West Ham spokesman
Having failed in their attempt to have the original punishment overturned, the Yorkshire club invoked a Football Association rule that allows clubs with a legal dispute to go before an independent tribunal.
McCabe told his club's official website: "I can confirm that both clubs have been notified of the ruling. The arbitration panel has awarded in our favour.
"The matter is still legally in process so I do not wish to comment any further until we have completed that process."
A club statement added: "The Blades began their legal fight for reinstatement some 16 months which also included an arbitration hearing against the Premier League.
"This award could now pose a question as to what the Premier League will do."
Sheffield United's claim was considered by former MCC president Lord Griffiths, Sir Anthony Colman, a former High Court judge, and Robert Englehart QC.
A West Ham spokesman told BBC Sport: "We need to digest the full findings of the arbitration panel and will consult our lawyers on the next steps we might take before making any further comment.
"It would not be appropriate to comment further at this stage."
BBC Sport understands that the Hammers are considering an appeal and could decide to take the case to the Court of Arbitration for Sport in Lausanne, Switzerland.
Tevez and Mascherano were brought to Upton Park from Brazilian club Corinthians on the final day of the 2006 summer transfer window.
The pair were judged to have been partially-owned by Kia Joorabchian's Media Sports Investment (MSI) company.
They have subsequently moved on to Manchester United and Liverpool respectively.
With nine matches remaining in the 2006/07 season, West Ham were rooted to the bottom of the Premier League and 10 points adrift of safety, while Sheffield United were two places above the drop zone.
Tevez scored five goals after this, including the winner against Manchester United at Old Trafford on the final day of the season, to secure West Ham's survival.
Wasn't expecting this to be honest. Will this ruling hold up or will this not be the end?
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