In line with James Gunn's upcoming Marvel Comics film sequel "Guardians of the Galaxy: Vol. 2," it has been rumored that "Rocky" and "Creed" star Sylvester Stallone is set to join the film's growing cast ensemble and is rumored to play Star-Lord's father.

According to The Independent, it seems like action star Stallone is set to join Kurt Russel, Chris Sullivan, Elizabeth Debicki, Tommy Flanagan, and Pom Klementieff in the expanding cast of Gunn's Chris Pratt-led film "Guardians of the Galaxy: Vol. 2."

Stallone was previously seen holding a script and leaving the Atlanta hotel, the site where the film's cast members are staying, according to New York Daily News. According to the publication, the "Rocky" actor was also seen getting into the car which was usually assigned to the film's lead star Pratt.

The Daily News writes that the reason why Stallone was on the "Guardians of the Galaxy: Vol. 2" set is unknown; however, rumors say that the "Creed" actor is set to have a cameo on Gunn's forthcoming film sequel.

Fans have linked "The Hateful Eight" star Russel to the role of Peter Quill/Star-Lord's father, but with the latest reveal of Stallone's inclusion in the film, rumors have surfaced that the latter could play the role instead.

"Guardians of the Galaxy: Vol. 2" stands as the sequel to Gunn's 2014 film "Guardians of the Galaxy." According to previous reports, the sequel is set to explore the characters deeper, allowing fans to get to know them better. The film is also believed to touch the story arc involving Quill and his father, who was not present in the first film.

Aside from Stallone, Russel, and the aforementioned stars, the film also stars Karen Gillan, Vin Diesel, Bradley Cooper, Dave Bautista, and Zoe Saldana, among others.

Gunn's "Guardians of the Galaxy: Vol.2" is set to premiere in theaters in the United States on May 5, 2017.