Robert Downey Jr. and Paul Thomas Anderson have been friends for a while now. "I just think he's one of our great American directors," Downey said of Anderson to MTV in 2011. "I just like hanging out with the guy."

Those hang-outs almost extended to the film set: Downey and Anderson had discussed working together on the director's adaptation of Thomas Pynchon's "Inherent Vice," a rumor Downey said was "probably true" during that same MTV intervew. "We tend to talk about a variety of potential projects, and Thomas Pynchon's 'Inherent Vice' could be great. We'll see."

It could have been great, but Anderson cast Joaquin Phoenix in the film earlier this year. Phoenix, who worked with Anderson on "The Master," is set to play "Inherent Vice" lead character Doc Sportello, a stoner detective working on a kidnapping case in 1969 Los Angeles. Why did Anderson pick Phoenix over his pal Downey?

"I think he told me I'm too old," Downey joked to GQ in a new interview. "Which I love when people tell me." Downey recently turned 48; Phoenix is 10 years his junior.

Not that Downey minds. As the "Iron Man 3" star notes in the GQ profile, he and Anderson have a relationship that thrives on mockery.

"He goes, 'How does it feel to be the shortest superstar in the world?' And I say, 'It's amazing. And who tagged on that other act in the movie after Joaquin drove off on the motorcycle? Because the movie ended there, right?' He just laughs," Downey said, referring to the last act of "The Master." "We live to rib each other, because he is as far on one side of the scale as I am to the other, presently, in people's perception, and yet we could finish each other's sentences all day."

"Inherent Vice," with Phoenix in the lead role, is supposed to start filming later this year. For more on Downey, including what he thinks of that reported $50 million payday he earned for "Marvel's The Avengers," head over to GQ.

[via GQ]

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