From “Mean Streets” to their upcoming “The Irishman,” Robert De Niro and Martin Scorsese have one of film’s most famous (and long-running) actor/director partnerships.

The two talked about their decades of work together at the Tribeca Film Festival (which De Niro co-founded) on Sunday afternoon, touching on the dynamics of their partnership, Scorsese’s hesitance to take on certain projects and even another frequent collaborator: Leonardo DiCaprio, who happened to be in the audience for the chat at the Beacon Theater.

See highlights from the two’s wide-ranging talk below.

‘Raging Bull’ Almost Didn’t Happen

Scorsese was hesitant about and “overwhelmed” by “Raging Bull,” their 1980 boxing biopic, from the start. The director explained that he didn’t “understand boxing,” and had to realize that it was really about the athlete himself, Jake LaMotta (played by De Niro), rather than the sport. But that wasn’t the only obstacle the movie faced in getting made.

Scorsese described a meeting with Irwin Winkler, one of the film’s producers, in which two they were joined by two studio execs. They questioned them about the film in what they thought was a normal check-in on their progress.

“I don’t to make a film about this guy,” Scorsese recalled one of the execs saying. “This guy is a cockroach.”

“And so your reaction was articulate and it was grand, in a sense,” he went on to De Niro. “You said, ‘No he’s not.’”

Scorsese later learned from Winkler’s memoir that the execs were on their way to shut down the movie. Luckily, the duo managed to convince them otherwise.

Scorsese Got a Letter From Terrence Malick About ‘Silence’

In describing the inspiration behind “Silence,” his 2016 historical drama, Scorsese went in-depth on his relationship with religion.

“For me, that faith that I was instilled with as a kid – that changes,” he said. “Ultimately, it’s been a long kind of struggle – I’m not finished, of course – but a struggle toward a mature faith, whatever that is.”

Saying “Silence” is about “the struggle toward the very essence of faith,” Scorsese revealed Terrence Malick sent him a letter after he saw the film. In it, Malick asked, “What does Christ want from us?” “That’s interesting,” Scorsese noted.

Leo’s Here!

Though he didn’t participate in the panel, Leonardo DiCaprio, who has worked with Scorsese on five films, was in the audience, keeping it low-key under a baseball hat – until, of course, Scorsese and De Niro called him out, leading to a long applause from the crowd.

De Niro, in fact, was the one who first told Scorsese about DiCaprio. De Niro had worked with DiCaprio, who would later convince Scorsese to take on “The Wolf of Wall Street,” on “Boy’s Life” back in 1993. “There’s this kid, Leo DiCaprio,” Scorsese recalled De Niro telling him. “He’s really good. You’ve gotta work with him sometime.”

“It was extraordinary fortune, because he liked the kind of pictures we made,” Scorsese said of DiCaprio. “And he wanted to make movies like that, in a way. In other words, not being afraid of certain topics… and he was more concerned with the truth of a character, and of a situation. And he wasn’t afraid to go anywhere with this stuff.”

De Niro Had to Really Convince Scorsese to Make ‘King of Comedy’

De Niro “dragged” Scorsese into making 1982’s “The King of Comedy,” the actor admitted. Scorsese, for his part, revealed that he originally saw the script as a “one-line gag.”

What he missed at first, Scorsese said, was the look at celebrity and fame. He was watching De Niro rise to the A-list and dealing with all that comes with it, while he, behind the camera, didn’t have the same experience in the spotlight.

“You started experiencing fame in a different way after ‘Godfather,’” Scorsese told De Niro. “You were experiencing this and I was not. So I didn’t quite understand the gravity.”

Once the film was released, Scorsese said it was “reviled” (while it did receive mostly positive reviews, it was a flop at the box office). The movie was accused of pointing the finger at the media, he remembered, but would later be more critically appreciated.

A Brief Tease on ‘The Irishman’

The two revealed very little about “The Irishman,” their next collaboration that’s headed to Netflix likely later this year. They did tease, however, that it’s “in the milieu of the pictures we’ve done together.”

“But I think and I hope from a different vantage point,” Scorsese added. “The years have gone by and we see things in a special way.”