Mon-El (Chris Wood) gets into a fist fight with Cyborg Superman (David Harewood) in a sneak peek for Season 2, episode 8 of “Supergirl.”

The minute-long clip opens with Mon-El leaving his seat inside National City’s alien dive bar to follow a hooded man out of the establishment. The Daxamite thinks that the guy is J’onn (Harewood), so he’s taken aback when the man turns around and greets him with a punch in the face. Mon-El tries his best to fight back, but the guy — who is actually Cyborg Superman — is obviously much stronger than him.

The real problem, however, is the gaseous substance that Cyborg Superman unleashed inside the pub, which seemingly kills several of the alien patrons in an instant. While it’s unclear what exactly that substance is, it probably contains Medusa.

“Medusa plays very strongly in the next episode … and it’s basically a virus,” series actress Brenda Strong said in a recent interview with Entertainment Weekly. “It’s one of those exclusive viruses that don’t touch anyone whose organic material is human. It only attacks anything that is alien, and it’s a big one. So, that poses imminent threat to the planet.”

In Season 2, episode 7, titled “The Darkest Place,” Lillian (Strong) took some of Supergirl’s (Melissa Benoist) blood which Cyborg Superman later used to hack into the system of Superman’s (Tyler Hoechlin) arctic sanctuary, Fortress of Solitude. At the end of the episode, Cyborg Superman managed to order the facility’s Kelex to give him every detail there is about Project Medusa.

When asked how Lillian — the woman who runs CADMUS — knew that Superman (Tyler Hoechlin) had the Medusa virus, Strong told Entertainment Weekly: “Well, [probably from] the underground intelligence world … She’s a scientist, so I’m sure there are things about alien life forms that she’s aware of. Obviously, she needed to weaken Supergirl enough so that she could take her blood in order to have the key to unlock what was there and to get ahold of it.”

“Supergirl” Season 2, episode 8, titled “Medusa,” airs on Monday, Nov. 28 at 8 p.m. EST on The CW.