Real Madrid wonderkid Franco Mastantuono has been told he must toughen up and show significantly more bravery if he wants to succeed at the Bernabeu. Argentina legend Mario Kempes believes the 18-year-old is currently failing to reach his potential and has urged him to emulate Barcelona rival Lamine Yamal while outworking superstars like Kylian Mbappe to survive at the club.Mastantuono arrived in the Spanish capital last summer carrying the weight of a massive reputation and a transfer fee to match. Madrid parted with more than €60 million to secure his services from River Plate, viewing the midfielder as a cornerstone for their future dominance. However, following a bright start to life in La Liga, trouble with injury has resulted in the teenager’s form dipping in recent months, leading to concerns that he is struggling to adapt to the relentless demands of arguably the biggest club in world football.Kempes, a World Cup winner and one of Argentina’s greatest-ever players, has offered an honest assessment of his compatriot's predicament. Speaking in an interview regarding Mastantuono’s regression, the 71-year-old warned that the patience afforded to young talents in South America does not exist in Madrid."It’s not easy, it’s not River, it’s not Boca… it’s Real Madrid," Kempes stated. "At Real Madrid, you have to win even in training. Mastantuono needs to be a little more daring, he needs to be more courageous."Kempes also cautioned that if the youngster does not start utilising the talent that earned him the move, his time in Europe could be cut short. "If they brought him from River to Real Madrid, it’s because they saw potential in him, and today that potential isn’t working in his favour. If he doesn’t use that potential, he won’t last long."In what might be considered a bitter pill for Madridistas to swallow, Kempes pointed to the arch-enemy for a blueprint on how a teenager should handle the pressure of elite Spanish football. He cited Barcelona’s Yamal as the perfect example of the "boldness" that Mastantuono is currently lacking, directly linking that attacking fearlessness with the need to work harder than the established 'Galacticos' in the squad.Kempes urged Mastantuono to rediscover the swagger he showed at River Plate, insisting that until he has the catalogue of goals and trophies to match illustrious teammates Mbappe and Vinicius Junior, his value must come through unceasing effort and risk-taking."He needs to get bolder, do what he did at River, shoot from outside the box, take on defenders… Lamine Yamal is more or less like that, look, he loses the ball, not often, but he does lose it, and he keeps asking for it. And he takes on defenders, and he shoots, and he plays. That’s what Mastantuono has to do, sacrifice himself 20 times more than Mbappe, or Vini, or anyone else. Even Rodrygo."Looking for smarter football bets? Get expert previews, data-driven predictions & winning insights with GOAL Tips on Telegram. Join our growing community now!Kempes addressed the psychological aspect of the move. Transitioning from being the jewel of River Plate to just another prospect in a galaxy of stars can be jarring. The legend dismissed the idea that "mental sharpness" in theory is enough; it must be translated into tangible actions on the pitch.He warned Mastantuono against becoming a passenger who relies solely on effort without end product. "Mentally? You have to prove it on the field, not just because you’re mentally sharp," Kempes argued. "People will like you, yes, they value your effort, your will, but you have to be a protagonist, not just in some things. Believe you can be a star, but without letting it go to your head."Add GOAL.com as a preferred source on Google to see more of our reportingWhile the signing was clearly made with the long term in mind, the sense of regression in recent months has raised alarms, but Mastantuono recently addressed those concerns, saying: "Since I was a boy, people have talked about my football; it could be said that I was the new Messi and at the same time a disaster, the worst purchase of Real Madrid. I don't believe I am Messi, nor do I believe I am Real Madrid's worst signing. I work for my best version, which I know I can have."With the business end of the season approaching, coach Alvaro Arbeloa will need his entire squad firing. A revitalised, "daring" Mastantuono who is willing to take risks and outwork the stars around him could yet prove to be the difference-maker they paid a fortune to acquire.