Eddie Redmayne Recalls Not Recognizing Robert Pattinson at Gym Because He Was 'So Physically Changed'

Robert Pattinson was unrecognizable to his longtime friend Eddie Redmayne after his physical transformation.

In an appearance on The Tonight Show with host Jimmy Fallon Wednesday, the 40-year-old Fantastic Beasts: The Secrets of Dumbledore star reflected on a funny time when he ran into Pattinson at the gym. During the encounter it was difficult for Redmayne to recognize Pattinson given his fitness transformation in preparation for The Batman.

"When we made Fantastic Beasts it was at the same studio that Rob was making Batman and we shared a gym because my character and my body is so buff," Redmayne joked, adding, "One day I went to the gym and I walked in and there was this guy with a high ponytail, massive, doing the most extraordinary stunts I've ever seen with his stunt director."

He continued, "I walk in and there's this guy and this guy goes 'Hi' and I go 'Hi' and then I just sort of sit there watching him do these incredible things while I sort of weakly do a sit-up in the corner."

"As I'm going, this guy goes, 'Bye, Eddie!' And I look back and it was Rob," said Redmayne. "He was so physically changed and he had a man bun and what I'd seen him do was so dumbfounding. He completely transformed himself."

Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.

Redmayne and Pattinson go way back: Pre-fame, they were in a roommate friend group in Los Angeles along with now-famous actors Jamie Dornan, Andrew Garfield and Charlie Cox.

In January, Pattinson admitted he did indeed beef up to play Batman. At the time, Pattinson chatted with MovieMaker about his role as the titular Caped Crusader, revealing that comments he previously made to GQ about his work in the gym (or rather, lack thereof) to get ready for the film "came back to haunt [him]."

RELATED VIDEO: Robert Pattinson on the Surprising Challenges of His Batsuit: 'You'd Get Trapped in Rooms'

"I just always think it's really embarrassing to talk about how you're working out," said Pattinson, laughing. "I think it's like an English thing. Unless you are in the most unbelievable shape, where people are just genuinely curious, going, 'How have you achieved, like, physical perfection?' or whatever."

Pattinson's initial comments to GQ for a June/July 2020 cover story included the Twilight alum saying, "I think if you're working out all the time, you're part of the problem."