Robert Downey Jr. surprised ‘Doomsday’ directors with ‘Doctor Doom’ voice

Robert Downey Jr. left directors stunned with his Doctor Doom voice.

The actor, who is currently working on ‘Avengers: Doomsday,’ surprised directors Anthony and Joe Russo, with his immaculate voice over as Doctor Doom.

Speaking with PEOPLE at San Diego Comic Con following Marvel’s presentation for the, the directors behind Doomsday noted: “That was something that Robert surprised us with one day,” Anthony says. “You know, we were talking about all the details of the character — the voice, of course, is a key part of it, especially in the mask.”

“So one day I think it was in the trailer, we were just sort of talking about some ideas and he broke out into the voice,” Anthony continues. “And we knew at that moment, that was it.”

“I mean, it was one of those moments. It’d probably be one of the more memorable moments. —that and the ‘I Am Iron Man’ [sequence] when he snapped his fingers,” Joe says.

“Robert tends to present a lot of those super memorable moments,” said the brothers.