Atletico Madrid striker Falcao is at the centre of a payment dispute between his current employers and former club Porto, according to reports in Spain.
The Colombian striker joined the club in 2011 for a reported fee of €40 million - plus €7m in incentives - with €18m of that total sum to be paid over two equal, yearly instalments.
But Marca claims that Los Rojiblancos have paid only €6.5m of the required €9m, which was due on July 31st, and that could lead Porto chairman Pinto Da Costa to report the matter to Fifa.
However, Atleti sources claim that the Portuguese champions were well aware of this shortfall, and had already accepted their reasoning for not stumping up the full amount.
Indeed, the Spanish capital club are waiting to process €13.5m from the recent transfer of Eduardo Salvio to Benfica before they can fulfil their commitment to Os Dragoes.
Sanctions for failing to comply with transfer payments include a complete ban on incoming deals, which would be a hammer blow to Diego Simeone's preparations for the new Liga season.