The claim is over the player's earlier decision to unilaterally terminate his contract with them under Article 17 of FIFA's transfer regulations.
Sporting director Nando Pons told a press conference: "We are asking for 15million euros for the unilateral termination of the contract without just cause.
"It's a legal matter. We are not happy about it in the slightest, but Mallorca has to protect its interests."
Newcastle are due to meet Real in the Mallorca Summer Cup on Sunday, August 3.
And to add to the confusion ... former Magpies chairman Freddy Shepherd is on the verge of a takeover.
That in itself can cause bad blood, because Newcastle owner Mike Ashley allegedly banned Shepherd (and his family) from St James' Park ... which was a massive blow to the die-hard Geordie.
This pre-season fixture could be very interesting.