The frightening UFC 217 knockout you probably didn't see

Forget Georges St-Pierre's incredible comeback and three titles changing hands, the most brutal moment of UFC 217 happened during the undercard.

With all eyes waiting on the highly anticipated return of GSP against middleweight champion Michael Bisping, veteran fighter Ovince Saint Preux served up a sharply spiked appetiser during preliminaries at Madison Square Garden.

Standing on the wrong side of what was looking like a unanimous decision in favour of Corey Anderson, Saint Preux landed a brutal head kick knockout on his opponent, six years his junior.

Yikes! Image: Getty

The Florida native is regarded as one the most prolific finishers in the light heavyweight division and midway through the third and final round, he added to that reputation with a left-foot blow that turned Anderson’s lights out.

The come-from-behind victory was his third straight in the division and took his career record to 21-10-0.

Go to sleep. Image: Getty

St-Pierre completed his stunning comeback by beating Bisping by submission after a four-year absence from the octagon.

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The 36-year-old choked reigning champion Bisping into unconsciousness at the end of the third round to claim the belt after a thrilling back-and-forth battle on a night when three UFC titles changed hands.

Fighting for the first time in a heavier weight class, former welterweight champion St-Pierre, who walked away from the sport in his prime in 2013, had the better of the early exchanges, rocking the Briton several times.

At the end of the third round St-Pierre sent Bisping crashing to the canvas, and he followed up with a series of brutal elbows before taking the Englishman's back and applying a rear naked choke hold to finish the fight.

Rather than concede defeat, Bisping lost consciousness before referee John McCarthy stepped in to stop the fight.

"I don't have a word in my mouth right now. It's a dream come true guys, thank you for the support," a bloodied St-Pierre told the fans.

"He hurt me very hard. A few times I got stunned, I tried to hide it, I wouldn't like to do that fight again."

Earlier in the evening, challenger Rose Namajunas pulled off a stunning victory to wrest the women's strawweight crown from Joanna Jedrzejczyk, felling the Pole with a thundering left hand to finish the fight by knockout 3:03 into the first round.

The men's bantamweight title bout threw up another instant classic as TJ Dillashaw floored Cody Garbrandt halfway through the second to win by knockout and reclaim the belt he lost to Dominick Cruz in January 2016.

with AAP and Cagewriter