Santos, 18, is a Barca target, with the Catalan giants having tapped into the South American market over the years.
The defensive midfielder is earning plaudits for Brazilian side Vasco da Gama, making 36 appearances, and scoring eight goals.
Barcelona are in the market for a new defensive midfield signing with the likelihood of veteran Spaniard Sergio Busquets leaving at the end of the season.
They have been linked with many top names, including Wolverhampton Wanderers' Ruben Neves, but Santos has been on their shortlist for a while.
The Brazilian teenager only signed a new contract with Vasco in September, which expires in 2027.
There is a €40 million release clause in his new deal.
Barcelona may need to move quickly, however, as the prior report claims:
"Newcastle seems determined to take the cat to the water and will bid hard for him."
Eddie Howe has overseen an impressive transformation of the Magpies since taking over in November 2021.
Newcastle are third in the Premier League, winning eight, drawing six, and losing just one of their 15 fixtures.
Santos would follow in the footsteps of his compatriot Bruno Guimaraes if he does head to St James' Park.
He can transition from a defensive midfielder into a box-to-box asset, and his eight goals show that he has an eye for goal.
Selecao legend Juninho heaped huge praise on the Vasco teenager, telling Brazilian outlet Globo:
“Physically he is a monster. Without the ball, his participation is total. I even wanted to see his GPS, because he doesn’t stop. And technically he is far above the others."
Barcelona's Busquets claims that he is free in January
Barcelona midfielder Busquets has hinted that he will leave Camp Nou at the end of the season.
The 34-year-old was a guest on former Barca striker Sergio Aguero's Twitch stream.
Busquets' contract with Barcelona expires next summer.
He stunned the Manchester City legend when he claimed he would be available in January, alluding to the fact that he could talk to clubs at that time.
The Spaniard said:
"I'm free in January."
Busquets has been an ever-present for the Blaugrana since making his debut in 2007.
He has made 696 appearances, scoring 18 goals and providing 42 assists.
The veteran midfielder has had difficulties this season amid a poor run of form and backlash from fans over his performances.
The Barca man has made 16 appearances across competitions, helping the side keep nine clean sheets.