Manchester United and Chelsea target John-Obi Mikel is to appeal against a court's decision not to consider his contract dispute with Lyn Oslo.
Mikel signed a deal with Man Utd in April
His lawyers allege the contract with the Norwegian club was forged.
If it is proved, then the 18-year-old midfielder's deal with United, who he believes he was pressured into signing for last April, would become invalid.
"The ruling is wrong," said lawyer Helge Morten Svarva, who is taking the case to the Oslo appeals court.
Nigerian Mikel has been told by the city's district court to pay Lyn Oslo 150,000 kroner (£13,000) in legal costs, which Svarva also said would be contested in the appeals court.
Chelsea have also become embroiled in the saga, with United and Lyn writing to Fifa claiming that agents acting on behalf of the Blues attempted to induce the player to breach agreements he had made.
They want Fifa to consider imposing a transfer ban on Chelsea as well as barring them from certain tournaments.