‘What the f**k is that?’ Fighter floors foe then heads him in crotch on top of condom advert in bloody UFC Vegas 23 win (VIDEO)

Baffled fans have seen UFC light heavyweight Da Un Jung grapple with rival William Knight before appearing to repeatedly move his head back and forth from his groin – with the bizarre move playing out on top of a sign for condoms.

Unbeaten South Korean MMA star Jung performed eight takedowns on his way to a unanimous decision win over UFC newcomer Knight, including the suspect-looking moment when an overhead camera appeared to show him going at his rival's crotch area with his head.

Shocked viewers spotted that the unorthodox action was taking place right on top of a sign on the canvas for a condom and lubricant brand, adding to the mirth amid an often-gory display of wrestling.

"Great head movement," joked one observer. "That's how you increase efficiency of this kind of job."

Another said: "I've seen this in a movie before."

Contender Series standout Knight appeared to be bleeding heavily for much of the fight. "It was either from side control or half-guard," explained Jung, admitting that Knight had been a heavy hitter.

"I pushed away on his head, had an underhook and I did a snap elbow from the top. I felt it hit the bridge of his nose and he started bleeding after that.

"I felt that because of the damage to his nose, he might tire even faster. It was very short notice for him and I told him that I knew he wasn't on his best form because of the time change.

"I think he took it on 10 or 14 days. I knew I wasn't fighting the best version of him but I thanked him anyway."

New father Jung is now aiming for the very top. "I want to be the best fighter that Asia has ever produced and I want to be world champion," he said.

"I haven't thought about the timeline, but it might take a little while."