Avengers: Infinity War will feature more Marvel superhero characters than any film before it. With the knowledge that the Marvel cinematic universe has been building toward a showdown with Thanos almost since the beginning, most fans have assumed that the Guardians of the Galaxy will be among them, possibly to partner up with the Avengers in order to combat the universe's biggest, baddest villain and his all-powerful Infinity Gauntlet.

That, however, hasn't been confirmed until now. In a recent live stream on Facebook, Vin Diesel (who plays Groot in Guardians of the Galaxy and its upcoming sequel) talked a bit about how the Marvel cinematic universe is coming together. He told the story of how after his first meeting with Marvel, he took a picture that included a copy of the Avengers in the background.

"What's gonna be surreal is that picture is going to come to pass because now the Guardians will be included in Avengers: Infinity War and that's incredibly exciting," Diesel said during the live stream. "Incredibly exciting and something that if you were a part of our page you knew before everybody."

It's the first time anybody involved in the films has confirmed that the Guardians will appear in the third Avengers film, but exactly in what capacity remains a mystery. Will the two teams actually team up? Will the Guardians and the Avengers be working separately, but toward the common goal of defeating Thanos? How will Star-Lord and Iron Man get along? That's all unknown at this point.

What we do know is that Guardians of the Galaxy Vol. 2 will likely give fans some indication of where things are going, even though director James Gunn has stated that Thanos and the infinity stones are nowhere to be found in the sequel. The exact plot of the film is still unknown, but it was revealed at San Diego Comic-Con that it will feature the living planet Ego as Star-Lord's father, something which is not the case in the comics. You can read more about that here.

Meanwhile, Marvel recently announced that Avengers: Infinity War, which rolls out on May 4, 2018, is no longer a two-part film. The fourth Avengers movie, which is scheduled to premiere on May 3, 2019, has yet to receive an official title, making it a little unclear what exactly the film will be about.