The 22-year-old winger completed his £34.5 million move to Liverpool this week, triggering his release clause at Osasuna and signing a six-year contract at Anfield. Newcastle United had appeared to be in pole position for much of the preceding week, with Spanish reports claiming an agreement had been reached with both the player and Osasuna before Iraola's intervention changed the picture.
Speaking to Cadena SER, Muñoz explained how quickly the final decision was made: "It all happened very quickly. You can't turn down an opportunity like this."
On Iraola's role, he was direct: "He transmitted his confidence to me, the way his team plays. He played an important role in my decision."
The move fills the gap left by Mohamed Salah's departure from Anfield. Muñoz finished last season at Osasuna with seven goals and five assists in 34 appearances. Liverpool will pay the fee in two instalments, with Osasuna obliged to pass 50 percent to Real Madrid under the sell-on clause agreed when Muñoz moved to Pamplona for €6 million last summer.
Away from the transfer, his immediate focus is his recovery. A muscular problem picked up in Osasuna's penultimate league match against Espanyol prevented him from featuring in Spain's opening World Cup games despite making Luis de la Fuente's squad. The injury then flared again during the tournament.
"We were managing the injury, but I felt some discomfort again and we're trying to restart the process so I can get back on the pitch as soon as possible," he said. "These have been very difficult moments because this is a childhood dream and seeing it threatened by an injury is incredibly frustrating."
Luis De la Fuente has been careful with his workload since Spain arrived in North America. The group around Muñoz has helped him through the difficult days.
"My team-mates have been a fundamental pillar in making sure I wake up motivated every day," he said.
He also praised Spain's psychologist, Javier López Vallejo.
"Both before coming here and since we've been here, I've had my conversations with Javi," he said. "He helps me a great deal. He helps me see another perspective on everything that's happening here. It's a pleasure to have him."
Muñoz made clear the transfer noise during Spain's preparations was kept at arm's length: "I've been focused on the World Cup. I didn't want to hear much about my future unless it was something concrete."
He also paid tribute to Osasuna: "It's an incredible place. I'll always keep it in my heart. They gave me the best footballing year of my career."
Muñoz came through La Masia at Barcelona before joining Real Madrid's academy, where he made four senior appearances before dropping down to Osasuna. One season there changed everything.
Spanish reports suggest he could feature in the knockout rounds if Spain progress, potentially from the last 16. That is now his only focus: "It's the only thing I'm thinking about. It's a dream and I want to be back on the pitch as soon as possible."