Start up the "Rocky" theme music, because "Creed II" has officially entered production.

The upcoming sequel to the 2015 "Rocky" spinoff is due out in theaters this fall, and Sylvester Stallone is getting us all ready. As one of the film's star, producers, and co-writers, he has reason to be excited. He posted a video from the set on Instagram Monday and highlighted that it "seems like yesterday" that they were working on the last film, even if it's an "old cliché" to say.

"It's a very exciting moment to be here getting ready to Watch [sic] Creed 2 to commence filming," he wrote in part. "A very exciting day !!!"

The veteran action star added that the cast and production team have been patiently waiting to move forward with the sequel, and now he wants fans to "get ready to watch the fists startFLYING [sic]!"

Stallone reprises his role as Rocky Balboa in the film, a character he first portrayed 42 years ago, as he mentions in his video from the set. Back then, their setup wasn't quite as comfortable as it is now. "Progress is being made," he points out, which is true both in terms of their trailers and the work on "Creed II" itself.

None of the other cast members appear in Stallone's video, but he'll be joined in the film by Michael B. Jordan, who plays Donnie, the son of Rocky's former rival, the late Apollo Creed. Meanwhile, "Rocky IV" star Dolph Lundgren comes back as Ivan Drago, forcing Rocky and Donnie to deal with the past. Additionally "Creed" stars Tessa Thompson, Phylicia Rashad, Wood Harris, and Andre Ward are also returning. Let the fists start flying.

"Creed II" is slated to hit theaters Nov. 21.

[h/t: Slash Films]