Yesterday, Perez called a press conference at which he angrily denied the initial Marca story, and later the two players named by the newspaper - club captains
They claimed the newspaper's account of their lunch with Perez was "entirely false" and stated their support for Mourinho.
Perez had claimed that the lunch was only to discuss player bonuses, but Marca responded on Friday with a front-page story standing by their report.
"MARCA does not lie," its headline said.
The story stated: "The information published in this paper on Thursday regarding the dinner held last Tuesday at ACS headquarters between
The story was accompanied by a photograph of a text message from Marca's unnamed source - who they state is a player - reiterating that the conversation touched on several matters, including Mourinho.
"We spoke about everything. General matters, the dressing room, the manager, bonuses and the like," the text message said.
Marca had claimed that Casillas and Ramos warned Perez that several players would seek transfers if Mourinho continued as coach into another season.
To support that, Marca published fragments of a further text message which read: "It's not just (...), I'm telling you, there are many others."
After Real won the Primera Division at a canter last season, Mourinho has come under scrutiny this term after presiding over an indifferent run of results that has left the club trailing league leaders Barcelona by 15 points.
Reports of infighting between the outspoken coach, his playing staff and several club directors have never been far from the surface, while the former Chelsea and Inter Milan boss courted controversy recently by dropping captain Casillas from successive league games.
There have been high points this season, with Madrid safely into the last 16 of the Champions League and into the semi-finals of the Copa del Rey after completing a 3-1 aggregate win over Valencia in midweek.
However, that victory came at a cost with Casillas suffering a fractured bone in his hand which could see him sidelined for several months.