Anthony Mackie Can't Wait to Fight Robert Downey Jr.'s Doctor Doom in 'Avengers: Doomsday'

Few casting stories in recent Marvel history have been as surprising as Robert Downey Jr. swapping Iron Man’s armor for Doctor Doom’s cloak. For Anthony Mackie’s Captain America, that twist has created a matchup nobody could have predicted a few years ago. As ‘Avengers: Doomsday’ edges closer to its December 18 release, the actor has been sharing what it means for Sam Wilson to stand across from the man who defined the MCU’s early years.

Downey spent over a decade as Tony Stark, appearing in 10 Marvel films before his heroic exit in ‘Avengers: Endgame’. His return as Victor von Doom flipped that history on its head, turning Marvel’s most famous hero actor into its most dangerous villain. Meanwhile, Mackie inherited the shield from Chris Evans’ Steve Rogers, a handoff that has shaped the franchise ever since.

Now Mackie has made clear how much he’s looking forward to their clash. Speaking to SYFY Wire while promoting the audio production ‘Exoplanet’, he said, “I’ve always wanted to fight Robert Downey Jr.” The comment is playful, but it points to one of the film’s biggest selling points.

Mackie also offered a timeline clue in the same interview. He explained that ‘Avengers: Doomsday’ picks up just a few months after ‘Captain America: Brave New World’. In his description, Sam Wilson arrives with his mind set on reuniting the Avengers, convinced that the team has to come together to face a deadly new threat.

That fits with what Marvel’s own producers have said. Nate Moore has pointed out that there has never been an Avengers movie without a Captain America at its center, and he described the new story as one about Sam proving he deserves the mantle while being his own kind of hero rather than a copy of Steve Rogers. Mackie’s version of the character, after all, isn’t a super soldier, and that difference changes how he approaches a fight.

The matchup carries extra weight because Mackie and Downey have shared years of MCU history from the same side. Seeing them as hero and villain recasts that relationship in a completely different context. It also gives the film an emotional hook beyond the spectacle of a multiversal showdown.

Doom’s own build-up has leaned heavily on Downey’s input. The Russo brothers have said he developed his own backstory for the character and contributed costume ideas, and they have called the armor their favorite of any Marvel film they’ve directed. The more fans see of the villain, the clearer it becomes that the studio is betting big on his presence.

Mackie won’t be the only Captain America on screen, either. Chris Evans is returning as Steve Rogers, which means the film will feature both the original Sentinel of Liberty and the man who took over his role. Mackie has said he didn’t know about Evans’ return when the news first broke, which shows how tightly Marvel guarded the secret.

Their friendship has an interesting origin story, too. Mackie has recalled learning he would become the new Captain America when Evans let him read an early copy of the ‘Endgame’ script. The first trailer for ‘Doomsday’ even includes a moment where Steve Rogers summons Thor’s hammer Mjolnir, hinting at how the two eras of the character will collide.

He used to be different. Avengers: Doomsday arrives in theaters everywhere December 18. Get your tickets now: https://t.co/J5PUbxvAkc https://t.co/OUutSMZneq
— Marvel Studios (@MarvelStudios) August 15, 2026

Mackie has been teasing the tone of the film for a while. He has said it will feel like a return to the old Marvel spirit, which suggests the Russos are leaning into the kind of big, character-driven crossover that made their earlier ‘Avengers’ movies so popular. He has also talked about the personal cost of filming, including missed baseball games with his kids.

That mix of nostalgia and fresh stakes could be exactly what the franchise needs. The film brings together heroes from the Avengers, the X-Men and the Fantastic Four, all united against Downey’s Doctor Doom. And for Mackie, it’s a chance to finally get the face-off he has wanted for years.

With ‘Avengers: Secret Wars’ due on December 17, 2027, ‘Doomsday’ is only the first half of the story, but a Captain America showdown with Doom could be the moment that sets the tone for both films.