The Europa League holders still have to pay the Portuguese giants a sizeable amount from the deals which brought the duo to the Spanish capital last summerEuropa League winners Atletico Madrid still owe Porto €28.6 million (£23.1m) for the transfers of Radamel Falcao and Ruben Micael, according to a report in AS.
The Spanish side signed the duo from the Dragons in a combined deal of €45m (£36.4m) last summer.
Falcao scored two goals in this season's Europa League final as Atletico won their second European title in three years. Meanwhile, Micael joined Real Zaragoza on loan for the 2011-12 campaign.
In a report sent to market accounts and made public, it highlights that Los Colchoneros have yet to pay off more than half of the transfer fee.
The move was sanctioned in August 2011 under the mediation of agent Jorge Mendes, with Atletico confident that they will meet the payments agreed between the two parties.
Atletico ended the Primera Division season in fifth place.