In the footage, captured by a bystander, you can see the punch landed flush -- and knocked the Tampa Bay supporter out cold.
Cops say a witness told them the puncher then attempted to flee the scene. When a witness tried to stop him, the suspect allegedly punched the witness in the face too.
Eventually, police arrived on the scene and arrested the puncher, who they ID'ed as 29-year-old James Anastasio. Cops say he was booked on multiple charges of assault, disorderly conduct and harassment.
The Lightning fan who was KO'd, meanwhile, reportedly woke up several minutes following the punch ... and is in stable condition.