"He's Doc from Back to the Future!" Affleck teased. "He showed up to the table read and I had that pang of being starstruck, of seeing this guy emerge from off the screen. Particularly the movies you see as a young person can make such a big impression on you."
Just what level is Affleck's fandom at?
"I tried to ask him for his autograph," he admitted, "but I couldn't get the courage."
Guess Affleck had to settle for hanging out with fellow A-lister George Clooney, whom directed the film.
"I love George," Affleck added. "He's smart, he's funny, he's a great storyteller. He's fun to be around. He gets it. He's enormously charming and appealing, and it's because of his compassion and the amount that he cares about people and life and what happens in the world."
And Clooney's presence behind-the-scenes reminded Affleck of another mega-star: LeBron James.
"It's like playing on a basketball team with LeBron. It's a gift," Affleck noted, before quipping, "I told George I'm trying to negotiate a rate for him to come be my acting coach on my movies, but I can't afford him."
Affleck concluded, "It's an interesting year because it's been a hard year in a lot of ways, a tough year for a lot of people, but actually a very good year for me in terms of the quality of life and how I live. I've been very lucky. I've been very blessed."
Watch the full interview above!
The Tender Bar is playing in select theaters now, and hits theaters nationwide Dec. 22 before launching globally on Amazon Prime Video on Jan. 7.