Costa addressed reporters at the Estádio da Luz on Thursday, hours after Real Madrid officially confirmed Mourinho's appointment.
"In no circumstance do we remain at the mercy of anyone — we always control the situation. Every scenario was anticipated and analysed, and we were ready for whatever scenario emerged from the other side."
On the timing of Benfica's confirmation, Costa explained the delay had been deliberate.
"It was a process that took longer than we were initially expecting and forced us to be cautious and manage the situation so as not to make a mistake."
Asked directly about the €15 million release clause, Costa was clear that the money had not yet been received.
"We still haven't received the €15 million, but it is guaranteed and will arrive at any moment."
The clause itself has an unusual recent history. Earlier in 2026, a window existed during which Mourinho's termination fee was set as low as €3-7 million, available for a brief period after the end of the Portuguese league season. That window expired in late May before Real Madrid acted, and the figure rose to €15 million — a delay attributable, according to Costa, to the dependency on Florentino Pérez's re-election as Real Madrid president on June 7.
Costa confirmed that Benfica had offered Mourinho a renewal a month before his departure became official.
"The renewal proposal we made to him a month ago was presented at a moment we considered appropriate and when we wanted to keep him as coach of the Eagles. But José Mourinho's choice was different."
He also addressed what would have happened had Pérez lost the Real Madrid election.
"There was a gentleman's agreement — even in that scenario, Mourinho would not have continued as Benfica coach."
In a lighter moment, Costa addressed an AI-generated image of Mourinho in a Real Madrid shirt that circulated a week before the announcement, which he admitted had initially made him uncomfortable until he understood its origin.
On Marco Silva's appointment as Mourinho's successor, Costa was unequivocal.
"We believe he is the ideal coach for Benfica. His experience in England and what he has done gives us that hope. I am very satisfied with this choice."
The official confirmation of Mourinho's move to Real Madrid arrived this week, even though both clubs had completed every preparatory step beforehand. Some reports had suggested the formal presentation could be delayed until July — and Real Madrid have since confirmed Mourinho will join on July 13, the first day of pre-season.
For Benfica, the transition is now complete in every sense but one: the invoice.