Espí came on for the closing stages of Real Madrid's 2-2 pre-season draw with Fiorentina, replacing Endrick in the 74th minute and going close with a headed effort. Speaking to the media afterwards, he struggled to put the whirlwind week into words.
"I feel like the happiest man in the world. It's been three unbelievable days and I'm really happy," he said. "I haven't even been in Madrid 72 hours.
"I've trained with my team-mates, made my debut... really happy."
Asked how the move itself came together, Espí described a state of disbelief when the call finally arrived.
"At first I was in shock, I couldn't believe it. But in the end it was true. Mourinho didn't call me, but he received me — I hadn't even been at the training ground a minute," he said. He revealed the manager's instructions before sending him on: "That I should be myself, that I should be in the box, because the game was difficult, and that I should leave everything out there."
On what he can offer the squad, Espí kept his answer simple: "It's a dream. I'm here to help my team-mates, to give my all and make the most of every chance the boss gives me."
He has only been able to share the moment with part of his family so far.
"I've seen my parents, but not my friends or the rest of my family yet. I was in shock, sending photos of the shirt and everything. Really happy," he said, adding that he had kept the move a secret even under pressure from those around him.
"No, I didn't tell anyone. It was a stressful week, because it's news every player wants. Everyone asking me, and I couldn't say anything. It got a bit much, but I'm really happy."
Espí also spoke about settling into the dressing room, revealing a familiar face among the group.
"The young lads have really taken me under their wing. I already knew Joan Martinez, we're friends from Tavernes. And everyone in the first-team squad has surprised me — Arda Guler, Brahim, Valverde, Carreras, all of them," he said.
Asked about the strapping on his hand, he laughed off suggestions it was a nod to Karim Benzema: "I've worn it for three years because it hasn't gone badly for me. It's superstition."
He was similarly relaxed when asked if he had set himself a goals target: "No, I don't set a number. I'm going to give everything for the trust they show in me and help Madrid however I can."
Finally, asked what it means to potentially share a forward line with Kylian Mbappe and Vinicius Jr, Espí did not hide his excitement.
"They're among the best in the world. To see myself out there, next to them, is inexplicable. Unique. Really happy," he said.