Anthony Mackie has recalled his first heartwarming on-set interaction with Avengers: Doomsday co-star Ian McKellen.

Both Mackie, 47, and McKellen, 87, will reprise their respective roles of Captain America and X-Men character Magneto in the fifth installment of the Avengers franchise, out in theaters this December.

While Mackie took over as Captain America from Chris Evans at the end of 2019’s Avengers: Endgame, before officially embracing the title in the 2021 limited series The Falcon and the Winter Soldier, his casting in Doomsday was not immediately clear to McKellen.

“I go to Ian McKellen, he goes, ‘Hello, son.’ I’m like, ‘Ian McKellen, sir. You’re amazing. It’s amazing to work with you,’” he recently recounted to IMDb on the red carpet at San Diego Comic-Con.

“He goes, ‘So what are you doing in the film?’ and I’m like, ‘I’m Captain America,’” Mackie continued, expressing confusion while gesturing an arc around his head in reference to his superhero’s iconic circular, star-spangled vibranium shield.

“And he goes, ‘Wonderful... and you deserve that,’” he said, as the interviewer laughed. “Thank you, Sir Ian, thank you.”

Mackie has since portrayed the agile and strong superhuman in the latest Captain America iteration, Brave New World (2025).

Meanwhile, it’s been more than 10 years since McKellen’s latest appearance as mutant antihero Magneto in X-Men: Days of Future Past (2014). He originated the comic book villain in the 2000 film X-Men, later playing the character in X-Men: The Last Stand (2006), X-Men 2 (2006) and Days of Future Past. He additionally made a brief mid-credits cameo in The Wolverine (2013).

Avengers: Doomsday officially replaced Avengers: The Kang Dynasty, which was originally expected to star Jonathan Majors as Kang the Conqueror before he was convicted of assaulting his ex-girlfriend in 2023.

In the wake of the conviction, Marvel dropped Majors and rewrote and retitled the next Avengers film.

Premiering December 18, Doomsday will follow the Avengers as they team with the Fantastic Four, Thunderbolts and Earth’s other mightiest superheroes to save the multiverse from the evil Doctor Doom (Robert Downey Jr.).

Directed by brothers Joe and Anthony Russo, the film will welcome the return of several classic Marvel stars, including X-Men’s Rebecca Romijn and James Marsden and Thor’s Chris Hemsworth, alongside newer Marvel actors The Fantastic Four: First Step’s Vanessa Kirby and Pedro Pascal, Thunderbolts*’ Lewis Pullman and Florence Pugh, among others.

An extended trailer for the movie won over eager audiences at Comic-Con, following the release of an “underwhelming” first clip last week.