The 18-year-old moved to Santiago Bernabeu this summer, the club having agreed a €45 million (£40m/$52m) deal with Flamengo last year.
And he showed his worth during the derby, scoring twice, the first a clever finish after a bursting run from the left flank, the second a sublime long-range effort into the top corner.
However, it is the actions of Atletico player Tachi which have caught attention, as he tangled with Vinicius after a tackle.
With the pair on the ground, Tachi seemingly sank his teeth into the Brazilian's head, leaving the attacker aghast.
The referee only issued Tachi a yellow card, however, and also booked Vinicius for dissent, much to his chagrin.
Atletico's 20-year-old defender addressed his actions afterwards and admitted that he acted out of line.
He said: “I'm not proud of what happened and it does not reflect on how I am as a player.
"This action does not represent the values that the club instils in the academy and I know that it is not an example for the kids in the younger age groups. That incident does not represent my way of playing at all.
“In addition, it is a pity that this incident has generated so much publicity and eclipsed the good performance that the team put in against Castilla, as we had opportunities to win the match.
“At the end of the game I talked to Vinicius, we gave each other a hug and everything was fine. Now I have to learn from a situation like this and move forward.”
Real coach Julen Lopetegui was in the stands to witness Vinicius' performance, and the apparent bite that it included.
Indeed, Vinicius is set to spend the season with the Castilla side, with the club having numbers in attack after the signing of Mariano Diaz from Lyon.