Tuesday’s first leg of the knockout phase play-off tie was stopped for 10 minutes after Vinicius complained to French referee Francois Letexier about the alleged abuse following a confrontation between him and Prestianni.
That came just moments after Brazil international Vinicius scored the only goal in a 1-0 win before picking up a yellow card for his dancing celebration in front of the home crowd at the Estadio da Luz.
After arguing with Prestianni, Vinicius ran over to the referee and told him he had been called “mono”, the Spanish word for monkey, by the Argentine midfielder.
The 20-year-old Prestianni, who covered his mouth with his shirt as he appeared to say something to Vinicius, denies racially abusing the Real Madrid star.
Real’s England full-back Trent Alexander-Arnold said the incident had left a sour taste in the mouth.
“It’s disgusting. What’s happened tonight is a disgrace for football. It’s ruined the night for the team,” he said.
Real forward Kylian Mbappe called on Prestianni to be banned.
“We cannot accept there’s a player playing in Europe’s best competition and behaving like this,” the France captain told reporters.
“This guy doesn’t deserve to play in the Champions League again.”
Benfica coach Jose Mourinho hit out at Vinicius for inciting Benfica’s players and fans with his celebration.
“When you score a goal like that, you celebrate in a respectful way,” said the Portuguese.
British football anti-discrimination body Kick It Out criticised Mourinho’s reaction and accused him of “gaslighting”.
“When anyone reports discrimination in football, or anywhere, the first priority is that they are listened to and feel supported,” it said in a statement.
“Focusing on Vinicius Jr’s goal celebration or the history of the club, instead of acknowledging the report, is a form of gaslighting.
“This approach not only harms the individual affected but also sends the wrong message to others around the world who may have experienced similar situations.”
Benfica reiterated the club’s backing for Prestianni and said it “regrets a smear campaign of which the player has been a victim”.
Fifa president Gianni Infantino said he was “shocked and saddened” by the incident and praised the action taken by the referee, who initiated European football’s anti-racism protocol.
“There is absolutely no room for racism in our sport and in society,” Infantino wrote on Instagram.
“We need all the relevant stakeholders to take action and hold those responsible to account.”