EXCLUSIVE: This Is How Long Michael Fassbender Had to Train to Fight Himself in 'Alien: Covenant'

The actor discusses the 'tricky' nature of playing two different characters in this exclusive special featurette.

If you've yet to see Alien: Covenant, we are wading into light spoiler territory telling you that Michael Fassbender not only stars in the film, but also co-stars with himself. He plays two different androids, named David and Walter, and they ultimately do not get along.

"The fight stuff was a bit tricky," Fassbender explains in this featurette from Alien: Covenant's Blu-ray and DVD release, debuting here on ET. "Just learning both sides was a little bit of a head wrecker. But we got there in the end."

RELATED: Everything You Need to Know About the 'Alien' Franchise to Understand 'Alien: Covenant'

20th Century Fox

As for the specifics of how Fassbender filmed the sequences that required him to fight himself, the clip provides a behind-the-scenes look of him on set with director Ridley Scott and also reveals how long it took Fassbender to train ahead of shooting.

"Michael Fassbender spent weeks, hours on end, rehearsing," stunt coordinator Kyle Gardiner explains. "And it shows, because he's in both sides of the fight...To do one side and then the other [with] such an intricate choreography is super impressive."

Regrettably, the featurette does not continue on to show Fassbender filming the scene where he kisses himself, but when ET sat down with him and Scott ahead of the film's release, the actor revealed, "I was actually kissing a guy called Tom O'Sullivan, who was my double...Very close."

Alien: Covenant
arrives on DVD and Blu-ray on Aug. 15 and is available digitally now.

20th Century Fox