Bangor police said they were called to Diamonds Gentleman's Club around 3:20 a.m. Sunday.
They found the male victim who was bleeding from the head and learned the alleged attacker had fled toward Center Street.
It only took a few minutes before they found Gregory Watson, 37, of South Carolina at a nearby convenience store.
The investigation revealed Watson and Michael Ocean, 28, had assaulted two people earlier in the evening.
Watson is now charged with two counts of aggravated assault and Ocean is charged with assault.