Swansea City appeared in the Court of Arbitration for Sport on Friday over Dutch goalkeeper Michel Vorm's disputed sale to Tottenham.
Dutch club Utrecht claim they are owed a sell-on fee following his £1.5m move to Swansea in 2011.
The Swans maintain Vorm's move to Spurs in 2014 was a free transfer and they have acted correctly.
Utrecht have already had their case dismissed by world football's governing body Fifa.
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When Vorm joined Tottenham, Wales defender Ben Davies also joined Spurs in a £10m swap involving midfielder Gylfi Sigurdsson - a deal Swansea say was separate to Vorm's transfer.
Swans chairman Huw Jenkins appeared in court in Switzerland while Eredivisie club Utrecht were represented by director Wilco van Schaik.
The outcome of the hearing in Lausanne is not expected until next month.