Marvel Studios has promised for months that a trailer for Avengers: Infinity War will arrive before the end of the year. So far, fans have had to rely upon (now deleted) footage covertly recorded at Comic-Con International, and leaked screenshots. However, it looks as if the studio is about to make good on its promise, starting with just a simple number.

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This morning on their Facebook page, directors Joe and Anthony Russo posted an image of the number "3," leading to speculation that it's the beginning of a countdown to the release of Infinity War's first trailer on Thursday. That, or the teaser will arrive on Dec. 3.

Neither Russo brother has said anything further on the matter, and there was no mention of the Infinity War trailer in Vanity Fair's Marvel Studios cover story, also released today.

With a cast of dozens of characters from a decade's worth of movies uniting to stop the villainous Thanos, the scope of Avengers: Infinity War is larger than anything to come out of the Marvel Cinematic Universe thus far.

Directed by Joe and Anthony Russo, Marvel’s Avengers: Infinity War stars Robert Downey Jr., Josh Brolin, Mark Ruffalo, Tom Hiddleston, Chris Evans, Chris Hemsworth, Jeremy Renner, Chris Pratt, Elizabeth Olsen, Sebastian Stan, Benedict Cumberbatch, Paul Bettany, Samuel L. Jackson, Cobie Smulders, Benedict Wong, Zoe Saldana, Karen Gillan, Vin Diesel, Dave Bautista, Pom Klementieff, Scarlett Johansson, Tom Holland and Anthony Mackie. The film opens May 4, 2018.