When Alfredo James 'Al' Pacino started his acting career in earnest, Robert Downey Jr. was not even five years old. The future Sherlock Holmes actor, today also known for his Iron Man role in the Marvel Cinematic Universe, was born on April 4, 1965 in New York City. Three years later, on November 12, 1968, Al Pacino made his first major screen appearance of his career - in the fifth episode of the second season of N.Y.P.D., a police procedural drama that aired on ABC.

Downey Jr. kicked off his own career not too long after, when he played a puppy in the comedy flick Pound of 1970, which was written and directed by his father, Robert Downey Sr.

Downey Jr. and Pacino have both since gone on to become household names in their craft, and are now two of the most sought after actors in Hollywood.

Resembles Pacino In His Younger Days

Over the years, fans have often pointed out how much Downey Jr. resembles Pacino in his younger days. So much so that in one of Pacino's more recent works, where he was digitally de-aged, many people felt that Downey Jr. could have easily slotted in to play a younger version of his character.

In the 1980s, legendary director Martin Scorsese and acclaimed actor Robert De Niro had been trying to collaborate on a project. They worked through different ideas until more than two decades later, they landed on the novel I Heard You Paint Houses by Charles Brandt. Thus began the process towards the making of the film The Irishman which was eventually released in 2019.

Pacino and De Niro were joined on the cast by their equally seasoned colleague, Joe Pesci who specifically came out of retirement to star in this particular motion picture. The plot of The Irishman spanned multiple timelines, and the ageing actors' looks had to be digitally altered for their younger versions.

Al Pacino in The Irishman
via: The Verge

While modern technological advancements in visual effects mean the results were still quite believable, there were those who felt that it would have been better to cast different actors to fit into the earlier timeline.

RELATED: Netflix Wishes Happy Birthday To Martin Scorsese With BTS Clip From 'The Irishman'

'De-Aging Made Movie Hard To Watch'

This theory was also advanced by a user on Quora, whose bio on the platform reads, 'Produced screenwriter, former Sony Pictures script reader/story analyst, former Sony Studios liaison.' Miyamoto posed the question of which actors would have been best suited to play the younger roles, while putting forward suggestions of his own.

For a young Jimmy Hoffa (played by Pacino), Miyamoto suggested Downey Jr. For a younger version of Frank 'The Irishman' Sheeran (De Niro), he put forward Teenage Mutant Ninja actor, the Canadian Elias Koteas. He did add a disclaimer that Koteas, who is currently balding, would need an added hairpiece to complete the young De Niro look.

To finalize the lineup, Miyamoto proposed 54-year old Max Casella, famous for his work in The Sopranos and Boardwalk Empire, among others. One user concurred with the sentiments, stating, "The de-aging made that movie hard to watch."

Another challenged the choice of Downey Jr., citing his age as a potential hindrance. "Robert Downey Jr. as 'young' Al Pacino?! C’mon. He’s born in 1965," they stated. Yet another user did come to Miyamoto's defense claiming, "He’s 25 years younger than Pacino so that would work with just some makeup, most likely," one Diane McDaniel wrote.

RELATED: Robert De Niro Had This To Say About Dustin Hoffman's Acting Skills

War Of Words With Scorsese

Downey Jr. has not spoken publicly about whether he would be open to playing such a role, but he had a bit of a war of words with Scorsese around the time when The Irishman was released. Scorsese had famously criticized Marvel movies (which Downey Jr. is now synonymous with) and said that 'they were not cinema.'

Al Pacino and director Martin Scorsese
via: Esquire

Writing in a piece for The New York Times, Scorsese compared the franchise films with the kind of cinema he grew with. "For me, for the filmmakers I came to love and respect, for my friends who started making movies around the same time that I did, cinema was about revelation — aesthetic, emotional and spiritual revelation," he wrote.

He did admit that this perspective was not just a matter of his own personal preferences. "The fact that the films themselves don’t interest me is a matter of personal taste and temperament. I know that if I were younger, if I’d come of age at a later time, I might have been excited by these pictures and maybe even wanted to make one myself," Scorsese added.

These comments were put to Downey Jr. by radio personality Howard Stern, who then asked the actor whether he would class Marvel as cinema. The actor responded, "I mean it plays in theaters. I appreciate [Scorsese's] opinion. By the way, there is a lot to be said for how these genre movies, and I was happy to be part of the problem, if there is one."

NEXT: The Truth About Robert Downey Jr.'s Role In 'Tropic Thunder'