The Russo brothers don't expect Robert Downey Jr. to return as Iron Man.

The 59-year-old actor expressed an interest in reprising his role as Tony Stark/Iron Man in the Marvel Cinematic Universe (MCU) earlier this month but the 'Avengers: Endgame' directors cannot envisage a comeback after the character's death in the 2019 blockbuster.

Speaking to GamesRadar at the Sands International Film Festival, Anthony Russo said: "I don't know how they would do it. I don't know what the road to that would be."

Joe added: "I mean, we closed that book, so it would be up to them to figure out how to reopen it."

Robert confirmed last month that he would "happily" play 'Iron Man' once again and described the role as an "integral part of my DNA".

He told Esquire magazine: "It’s too integral a part of my DNA. That role chose me. And look, I always say, never, ever bet against Kevin Feige. It is a losing bet. He’s the house. He will always win."

Marvel boss Kevin Feige is unlikely to grant Robert his wish of an Iron Man return as he vowed not to "magically undo" the character's emotional passing in 'Avengers: Endgame'.

He told Vanity Fair last year: "We are going to keep that moment and not touch that moment again. We all worked very hard for many years to get to that, and we would never want to magically undo it any way."

Downey Jr. recently won the first Oscar of his career for Best Supporting Actor after portraying Lewis Strauss in 'Oppenheimer' and the Russos hailed the "redemption" story as the star's life had threatened to go off the rails as he battled drug problems.

Joe said: "His Oscar win was huge. It's amazing to live vicariously through Robert, you know, that experience for him is so profound, because of the journey he's had. I mean, it's one of the great stories of redemption.

"And he's such a lovely person, such a hard-working person. He's a generational actor, so that level of recognition for him, I think, was validation of his redemption arc."