Stan Lee has seen a lot of Marvel comics and characters, created by himself and others, adapted for film and television, however, he's never witnessed anything quite like Avengers: Infinity War.

RELATED: Spider-Man: Homecoming Teases a New [SPOILER] For Avengers: Infinity War

Star Robert Downey Jr. posted a photo from the legendary creator's visit to the set of the sprawling Marvel Studios sequel, accompanied by the caption, "I owe it all to you ..."

Greeting Lee alongside Downey are co-stars Benedict Cumberbatch and Tom Holland, and directors Joe and Anthony Russo. Because the photo was taken on a soundstage, it's difficult to say where, or when, the meeting took place.

It's worth noting that while Holland is clad in a knee-length jacket, he's clearly wearing a motion-capture suit beneath, which will undoubtedly fuel even more speculation in the wake of Spider-Man: Homecoming.

RELATED: Avengers: Infinity War Set Photos May Confirm Another Villain

Directed by Joe and Anthony Russo, Avengers: Infinity War boasts a sprawling ensemble cast that includes 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 arrives in theaters May 4, 2018, with the untitled sequel opening May 3, 2019.