The guy who knocked out Future's bodyguard with a flying blindside punch claims there's more to the story than the video shows ... and he was just protecting his friends.
As you'll recall ... the bodyguard was attacked last week at the Ibiza Airport after an altercation between the rapper and a group of guys carried over onto the street.
The man who threw the punch, Marcus, tells TMZ ... he and his buddies had just landed and noticed Future, so one of his pals asked for a picture. He claims Future responded with, "Suck my d**k."
Marcus admits his crew fired back at Future with some rudeness of their own, but says they were ready to leave and let it go ... but the bodyguard wasn't.
He claims the rapper's hired muscle followed them outside to the taxi line, and kept insulting and harassing them -- and even said he'd die for Future -- before inviting them to come around the corner to fight. Marcus' point is the guy was practically begging for it.
Marcus says the bodyguard continued to follow them in a threatening manner, and because he's a big guy and they didn't know what he was capable of ... he launched a preemptive strike.
The Brit also denies there was anything racially charged about the incident, and says his friends at the airport were predominantly black ... including the guy who shot the video. He's insistent he personally didn't drop any racial slurs.
As we told you ... Future's bodyguard isn't pressing charges for the assault and the Civil Guard of Spain will not investigate unless somebody does. Marcus claims he and his friends were detained by airport police shortly after the incident ... but were cut loose once cops reviewed security footage.
Future has denied any involvement in the ordeal ... other than turning down a photo request.