Ben Affleck loves directing his longtime friend Matt Damon.

The actor spoke to ET Canada’s Morgan Hoffman while promoting their new flick “Air”, which he directs and stars with Damon in.

When asked what his favourite thing about directing Damon was, Affleck, who was speaking alongside his co-star Chris Tucker, insisted, “I mean, he’s just so good. You know, it’s true. I think he’s kind of, I hate to say, like, kind of underappreciated.

“You don’t realize what a sublime actor he is because it’s so understated.

“He just has the capacity to find the character and say the lines and have it feel like completely authentic. And it’s not a showy skill.”

READ MORE: ‘Air’ Trailer: Matt Damon And Ben Affleck Change The Face Of Sports With The Air Jordan

With the pair being pals, Affleck admitted, “I didn’t even appreciate it [before]… I know the guy, you know, he’s my best friend.”

Not ending the praise there, he went on to point out that Damon was always “doing something interesting” and if there was a problem he’d “bail you out always.”

Affleck gushed, “He makes it make sense. He’s a director’s gift, really. All this cast is.”

READ MORE: Ben Affleck Says It’s A ‘Joy’ To Be Working With Jennifer Lopez On Upcoming Sports Movie ‘Unstoppable’

As well as directing, Affleck takes on the role of Phil Knight in the flick, while Damon plays Sonny Vaccaro and Jason Bateman stars as Rob Strasser.

The film goes behind the scenes of Nike’s partnership with the legendary Michael Jordan and the creation of the Air Jordan, which brought the company’s fledgling basketball division to life and revolutionized the worlds of sports and culture.

“Air” hits theatres April 5.