There's less than a month to go when Guardians of the Galaxy Vol. 2 hit theatres, but fans still have no clue about Sylvester Stallone's role in the upcoming Marvel movie.

Now, director James Gunn has finally opened up about the Expendables actor's role. He told SciFi Now, "Sylvester Stallone is a very important character. He's primarily a very important character to Yondu, played by Michael Rooker, who is honestly one of the stars if not the star of Guardians Of The Galaxy Vol. 2."

The director also teased Yondu's relationship with Stallone's character. He said: "Vol. 2 is as much Yondu's story as it is anybody else's and so his relationship to Sylvester Stallone, which in a way is another sort of fatherly relationship, is a part of the overall story."

"I love [Stallone]! I had such fun with him on set, and he's a really great guy, being somebody that, to me, was a true icon, like no actor I've ever worked with before, and it was a lot of fun and a surreal experience," The 46-year-old filmmaker added.

The movie has released many trailers, but they have been careful about not giving out any plot spoilers.

Gunn said that they have worked really hard to create a series of trailers that don't give away much of what's in the movie.

Admitting that keeping the trailers spoiler-free is a difficult task, Gunn said, "It's hard! The move takes a lot of twists and turns, and you talk a couple of steps into that and all of a sudden you've given away too much. But you want to sell the movie, and you want people to come and see it, so it's hard."

The film is scheduled to reach UK cinemas on 28 April 2017 and 5 May in the US.