It's been barely months since Palmeiras and Chelsea agreed to make Estevao Brazilian football's richest transfer, but the changes are already noticeable - and significant. Since his sale, the 17 year-old has not only won his first caps with Brazil - but outshone his hero and Real Madrid star Vinicius Jr in the process.
And beyond the praise raining down from the local press, Estevao's physical change is also catching the eye. His natural development being accelerated by Palmeiras' insistence that he go on a strict dietary plan. And the results are already showing: the teen, in just a few months, has added a solid 3kgs to his frame. The decision being made on the recommendation of coach Abel Ferreira, who had concerns about the slight stature of the winger when first promoted to senior training last year.
Mirtes Stancanelli, the club's nutritionist, has led the tailored programme and is delighted with the results.
"He knew he needed to gain a little more to support the games, training, etc., especially in the recovery stage, which was a little shorter, due to his body structure and metabolism," Stancanelli recently told ESPN Brasil. "In this sense, he gained slowly, understanding this, weight test after weight test, and if I'm not mistaken, it's been 3kg more so far, because we're taking it slow with him. Of these 3kg, there was a small increase in fat percentage, which is fundamental, and the gain in mass.
"And it's not like he started this path out of nowhere, he wasn't forced to do it all of a sudden. Over time, he saw the achievements he had, not only on the field, but also in terms of better nutrition, foods he never ate before, we worked and trained him on that."
As we say, Palmeiras are playing their part. Estevao will eventually leave, they know that, but he's still a valued player for the here-and-now. Between Palmeiras and the Selecao, Estevao has made 43 appearances, scoring 15 goals and providing ten assists. And he's still seven months away from his 18th birthday.
For many inside the Brazilian game, the hype is real. Genuine. Estevao is the best they've seen emerge since Neymar at Santos in the mid-2000s. Certainly his agent, Andre Cury, believes so. Indeed, Barcelona's former South American scout (proof enough of how significant a deal this is for Chelsea), is convinced Estevao is ahead of Brazil's captain at the same age.
"100%," declared Cury just days after Estevao's Chelsea agreement was announced. "He has quality, talent, speed, change of direction, intelligence. In fact, if you take Neymar at his age, he is above what Neymar was.
"At 17, Estevao plays better football than Neymar did at 17. Whether he will reach the same peak as Neymar, we will only know with time."
Brazil coach Dorival Jr, while reluctant to make the same comparison, has offered some encouragement about the type of footballing personality Chelsea will welcome next year. After handing Estevao his debut in the World Cup qualifying win against Ecuador, Dorival was asked about the similarities between Neymar, now of Al Hilal, and Brazil's newest cap.
"I rarely make comparisons that put two athletes together, in any sport," he began. "I can't do it... For me, each of them has their own particularities.
"Neymar is different. I also see qualities in Estevao, he has to be treated with care. He must maintain a professional attitude, be interested, and continue to seek corrections.
"He has natural quality, that's undeniable. This (working and seeking improvements) will make him take an even greater leap in quality.
"I hope he can develop all of this and have a brilliant career like the one (Neymar) mentioned."
But what about the man, himself. For Neymar, Estevao is a Brazilian guarantee.
"He is the best talent emerging in Brazilian football today. I think he will be a genius," declared the former Barca star - and this was before Estevao's Selecao breakthrough.
"I was very happy that my idol said that," Estevao later said after his maiden Brazil call. "He is a guy who, for us younger people, is a reference, an extra class, what he did in Brazil and in other teams is very difficult to do.
"(Neymar is) a guy we look up to, we try to do what he does on the field. It's very gratifying to know that my effort is being recognised day after day.
"Every day that passes I'm a bigger fan of his. Playing in Brazil isn't easy, there's a lot of pressure, a lot of criticism... He's a guy I really admire for the way he deals with it, it's important.
"We grew up watching him. I hope to be with him one day."
That prospect, as Neymar said himself, is as sure a bet as you'll get in football. And as Cury has insisted, there was no chance Estevao, nor Palmeiras, were going to allow things to slide after Chelsea's money had been banked.
"We still laugh about this together," said the teen's agent. "Estevao will keep up his performance. He'll play well, he doesn't feel it. He's always loved the ball and he'll always play well. Until the Club World Cup, he'll represent Palmeiras very well."
Then, in July, Estevao will formally become a Chelsea player. Even with €45m put away - another €16m due in bonuses (a sure thing inside 18 months, says Cury) - Palmeiras are holding up their end of the bargain.
The best since Neymar? In Estevao Willian, Chelsea are set to welcome a virtual guarantee - and Brazilian football will be hoping they're ready for it.