Robert Downey Jr. shares 'Avengers: Infinity War' set photo

Iron Man may fight Thanos onscreen, but when the cameras are off, the actors are just two motion-capture-clad bros.

#BTS with Brolin. #InfinityWar #Marvel #Avengers #BrolinWithTheHomies (📷: @jimmy_rich)

A post shared by Robert Downey Jr. (@robertdowneyjr) on

Marvel fans are itching to see the footage from "Avengers: Infinity War" that drove fans wild at the Disney D-23 fan club event last week, and again this week at San Diego Comic-Con. But the footage hasn't, and won't be released by Marvel, and it's unlikely fans will see it before sometime this fall. (Yes, there are leaked versions, no, we're not linking to them -- but you can read our take on the footage here.)

On Saturday however, star Robert Downey Jr. did share an Instagram image -- a double one, really -- showing himself with co-star Josh Brolin, who plays supervillain Thanos. Judging by the spots, the two actors appear to be wearing their motion-capture outfits.

Downey didn't offer much info in the caption, teasing only, "(Behind the scenes) with Brolin." There does seem to be a set behind the two men showing what could be the aftermath of an Avengers brawl.

The photo may not have been revealing, but it was popular, earning more than 650,000 likes in less than a day.

Seems like Marvel and its stars are playing this right -- by judiciously sharing only drips of "Infinity War" information, they're building up a huge reservoir of fan interest that can only sell more tickets eventually. 

"Avengers: Infinity War" is scheduled for a May 2018 release.