Franco Mastantuono leaves River Plate: When will the wonderkid arrive—and could he finish the FIFA Club World Cup with Real Madrid?

As one of the most expensive teenage signings in Argentine soccer history, Mastantuono’s move to Madrid has stirred headlines, digital buzz, and intense speculation about what comes next.

Franco Mastantuono may have just closed the chapter on his River Plate journey, but the Real Madrid story is only just beginning. Still only 17, the Argentine wonderkid is already experiencing the seismic impact of becoming part of soccer’s most powerful institution—even without officially wearing the club’s shirt.

As one of the most expensive teenage signings in Argentine soccer history, Mastantuono’s move to Madrid has stirred headlines, digital buzz, and intense speculation about what comes next.

Since the deal was confirmed, Mastantuono’s social media presence has skyrocketed. His Instagram followers have surged by over 200%, surpassing 1.8 million in mere weeks. Every photo, every post-match moment, and even casual training shots now go viral in minutes.

That fame has brought a wave of expectations, not just from fans but from the Madrid hierarchy too. At $70 million, Mastantuono is not a project—they see him as a long-term pillar of the club’s future.

When can Mastantuono officially join Real Madrid?

Despite River Plate’s early exit from the Club World Cup—where they secured just four points from three matches—Mastantuono is not yet eligible to join Real Madrid’s first team. While fans might expect him to walk straight into Xabi Alonso’s side, regulations state otherwise.

“Real Madrid won’t take any risks with Mastantuono’s registration,” reported Diario AS. Due to FIFA rules and internal club policy, the teenager cannot officially sign, register, or train with the team until he turns 18 on August 14. This cautious strategy mirrors Madrid’s approach with other South American talents like Vinicius Jr., Rodrygo, and Endrick.

Until then, he is not permitted to access Madrid’s Valdebebas training complex, and he will undergo a customized training program. Starting in late July, Mastantuono will relocate to Madrid, where he’ll prepare under the remote supervision of club fitness staff to adapt to the intensity of European soccer.

Club World Cup dream ends

Some had speculated that with the FIFA registration window opening on June 27, Mastantuono might switch shirts mid-tournament and join Real Madrid for the knockout rounds. However, that’s not possible.

FIFA regulations prevent a player from participating in the same tournament with two different clubs. “He cannot do so, basically because he was already present in the tournament,” confirmed Marca. So, for now, his Club World Cup journey is over—and his Madrid debut will have to wait.