The incident occurred at Lisbon’s Estadio da Luz following Vinicius’s spectacular winning goal, forcing referee Francois Letexier to halt proceedings for 10 minutes after initiating Uefa’s racism protocol.

Real Madrid teammate Kylian Mbappe insisted he heard Prestianni use a racist slur “five times” during the confrontation.

The 20-year-old Argentine has reportedly provided evidence to the governing body’s probe, claiming he called the Brazilian forward a homophobic term instead of “mono” – the Spanish word for monkey.

Madrid manager Alvaro Arbeloa urged Uefa to take decisive action against Prestianni, describing the incident as unambiguously racist.

Speaking at his pre-match press conference ahead of Saturday’s La Liga fixture against Osasuna, Arbeloa said: “Vinicius is sad, like all of us, and very indignant about what happened because, evidently, it was a racist act, which we don’t want to happen again.

“It’s in Uefa’s hands. They were the first to fight this battle many years ago, it’s a great opportunity for them to show that this fight is not just words, to take action and punish.”

The Spanish giants confirmed they had submitted “all available evidence” to Uefa’s investigation.

Uefa has not yet confirmed what the player said following the investigation.

Prestianni’s admission that he used anti-gay language rather than racist abuse could.

Uefa’s disciplinary regulations make no distinction between racist and homophobic discrimination when determining sanctions, meaning Prestianni’s admission was unlikely to change the outcome.

Article 14 of the governing body’s framework stipulates that anyone who “insults the human dignity of a person or group of persons on whatever grounds, including skin colour, race, religion, ethnic origin, gender or sexual orientation, incurs a suspension lasting at least 10 matches or a specified period of time, or any other appropriate sanction.”

Benfica manager Jose Mourinho has reportedly prohibited any discussion of Real Madrid within his squad.

The Portuguese boss was the centre of the row after suggesting Vinicius had provoked his players through exuberant goal celebrations at the corner flag.

He said: “When you score a goal like that, you celebrate in a respectful way.”

Mourinho revealed he had spoken directly to Vinicius during the lengthy stoppage, telling the Brazilian winger: “When you score a goal like that you just celebrate and walk back.”

Bayern Munich boss Vincent Kompany described those comments as “a huge mistake” in terms of leadership.

Arbeloa responded by defending his player: “Let’s not turn the victim into a provocateur. I think that would be unjustifiable, and I believe that nothing Vinicius did justifies a racist act.”

Benfica will be looking to overturn the deficit after Real Madrid secured a 1-0 triumph in the first leg.