In 2023, the forward became - at 16 years and 169 days - the youngest player to feature for Vasco da Gama in the 21st century, surpassing Chelsea's Andrey Santos.

But it was only last season that he really broke through.

"He belongs in the same bracket as boys like Estevao and Endrick," Gustavo Almeida, one of his earliest mentors at Vasco, tells BBC Sport.

"He's always gone toe-to-toe with those players. I even expected it to click for him earlier. But in football everyone develops in their own time, don't they? Everyone has their moment to blossom.

"He's a player who finishes really well from mid-range, from close in, with his head, with his left foot, with his right. He has a serious relationship with the goal."

Last year, Rayan ended the Brazilian league season third on the list for shots at goal - 92 in 34 games - scoring 14 times.

Vasco's fans have a song for him. It goes: "Oi, boa noite! Sera que hoje tem gol do Rayan?" It translates roughly as: "Hi, good evening! Will Rayan score today?"

And the 19-year-old regularly did - to the point that comparisons with Inter Milan legend Adriano gained significant traction.

"For me, Rayan is Adriano. But Adriano at Flamengo didn't do what Rayan is already doing. Adriano was often criticised back then. Rayan is already at a higher level than Adriano was [at the same age]," his former team-mate and Brazil international Souza said.

Adriano himself agrees: "He's definitely got parts of my game. He has everything he needs to make it. I hope he can do even better than I did."

Bournemouth fans hope so too.

It is almost as if Rayan were born at Vasco da Gama.

He is the son of Valkmar, a former Vasco centre-back who shared a dressing room with Romario and other superstars in the 1990s.

He grew up next to their stadium, and joined the club aged six. He established himself in the senior side, became a star and now leaves as their record sale.

"He has the potential to become one of the best players in the world," says Vasco head coach Fernando Diniz.

"He's tall, quick, left-footed, strikes the ball well, and he's started getting into the box and scoring with his head. He can play wide, as a false nine, as a number nine, or on the other flank. And I really like him as a person too."

Despite being hyped up from an early age, Rayan never let it get to his head.

"He even seemed a bit apart from it all. He was never a 'star' type, never cocky – quite the opposite," recalls Almeida, now an assistant coach at Cuiaba in Brazil.

"He didn't try to be the protagonist of the team. He just wanted to contribute in his own way, and he was always very simple about it – relaxed, easy-going, quiet."

His decision to join Bournemouth has sparked controversy in Brazil, where there has been a feeling that he was meant for a bigger club.

But it was a carefully considered step.

Rayan has always insisted that he wants to have a long career in Europe. He even sought advice from former Liverpool and Barcelona man Philippe Coutinho, now back at Vasco.

"I ask him [Coutinho] a lot. Some players go to Europe but end up coming straight back. So I say: 'Coutinho, help me. I want to make a name for myself too,'" he told Globo.

Ultimately, it will come down to how fast he can adjust to a new environment.

"Players from Rio can sometimes be less open to adapting," Almeida argues. "They often want to keep that Rio lifestyle - the beach, rice and beans, an easy routine.

"It'll be interesting to see if he's ready for this step. And hopefully a club like Bournemouth will provide a welcoming setting."

Rayan scored more goals in the Brazilian league in 2025 (14) than Chelsea's Brazilian youngster Estevao (13 in 2024), Real Madrid's Endrick (11 in 2023), Rodrygo (eight in 2018) or Vinicius Jr (four in 2018) managed in a single season.

It was no surprise when his name started being mentioned in terms of a Brazil call-up last year. But head coach Carlo Ancelotti left him out of his squad.

As much as no-one doubts his potential, he still has plenty of room to improve.

"His involvement in games fluctuates a lot," says a leading European scout who has followed him closely, speaking anonymously to protect relationships.

"He switches off at times. Sometimes, when he has to compete, he doesn't. Even though he's big, he isn't as physical as he could be.

"Tracking back to help the full-back, pressing... those modern-football demands are areas where he's still behind. Even at Vasco, people used to demand more intensity from him, to raise his tempo and increase his work-rate."

Rayan will also have to deal with the pressure of being the next Estevao.

They played together in the 2023 Under-17 World Cup in a team that included Manchester City's Vitor Reis, Wolves' Pedro Lima and Shakhtar Donetsk's Kaua Elias.

"I think the comparison with Estevao is going to be inevitable, because the expectation is often to find a new Estevao," Almeida concludes.

"Estevao is probably the best player I've worked with at academy level in my career. And Rayan has a lot of potential. I think he can reach a very high level and play for one of the big clubs in England – he has that in him."

Now he has to prove it at Bournemouth. Maybe not an issue for someone who has been hyped since he was 11.