DUSTIN POIRIER avenged defeat against Conor McGregor and in doing so sent shockwaves around the UFC.
Porier, who was knocked out by the Irishman in 2014, is one of the most experienced fighters in the lightweight division, also an ex-interim champion.
But it did not stop jaws from being dropped when he became the first man in the UFC to leave McGregor KO'd.
Poirier upset the odds and in doing left The Notorious facing questions over his fighting future.
Here we look at five of the UFC's greatest shocks in light of McGregor's devastating defeat on Fight Island. `
UFC 257: Poirier vs McGregor, 2021
McGregor was marking his return to the octagon, having had just 40 seconds of action in his last fight 12 months prior.
And he started the comeback bout well, landing frequently and defending well in the clinch.
But Poirier's calf kicks soon took their toll on McGregor, who was left with limited movement.
The American then capitalised in round two, as he backed McGregor against the cage and landed a barrage of punches.
After wobbling his opponent and dropping him with a right hook, a follow up shot down the middle closed the show and capped off an epic upset.
UFC 196: McGregor vs Diaz, 2016
Nate Diaz stepped in on just 11 days notice to face Conor McGregor, who was due to challenge for the lightweight belt against Rafael dos Anjos.
The Irishman instead moved up to welterweight as the featherweight champion, and exerted his energy trying to force to knockout early.
As he tired, Diaz took advantage and in round two submitted McGregor, who suffered his first UFC defeat, ending his run of supremacy.
The result shocked all due to McGregor's dominance up until that point mixed in with the fact Diaz was such a late replacement.
Diaz elevated himself to stardom, but The Notorious would enact revenge five months later, winning a five-round thriller at UFC 202.
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UFC 199: Rockhold vs. Bisping 2, 2016
Luke Rockhold and Michael Bisping built a steady rivalry following a prior sparring session between the pair.
Rockhold later beat the Brit in 2014, who was struggling in his championship ambitions having lost title eliminators.
But he was given a sudden chance at the title after Chris Weidman pulled out injured, allowing Bisping to fill in on 17 days notice.
The Manchester striker was already shooting for a film, so stayed in shape, and would stun Rockhold in round one with a check hook.
Bisping enjoyed an emotional celebration in the cage, and made one successful defence against old rival Dan Henderson before losing the belt to Georges St-Pierre.
UFC 193: Rousey vs Holm, 2015
Bantamweight queen Rousey looked unstoppable as she raced to 12-0 in her career - all by stoppage.
Former boxing and kickboxing champion Holly Holm was a 9-1 outsider and given little hope as the UFC broke their attendance record with 56,214 fans.
But the Marvel Stadium in Australia was shocked as Holm outstruck Rousey in round one before ending the fight with a brutal head kick in the second.
Rousey never recovered from the defeat and returned two years later, losing against Amanda Nunes, before moving to the WWE.
Holm lost the title in her next fight, and has failed in four more attempts to reclaim gold, but remains one of the UFC's biggest attractions.
UFC 162: Silva vs. Weidman, 2013
When Weidman challenged middleweight king Anderson Silva, the Brazilian was the face of the company.
Silva was seven years unbeaten as well as ten successful title defences into his reign and he had set the UFC alight with his unique striking and in-cage antics.
But the bravado caught up with him, as he fooled around for too long allowing Weidman to knock him out in round two.
The result left everyone stunned as Silva's cloak of invincibility vanished in a matter of seconds.
Weidman won the rematch five months later in gruesome circumstances as Silva snapped his leg while attempting a leg kick in the second round.
UFC 69: St-Pierre vs Matt Sera, 2007
When Matt Sera won the Ultimate Fighter in 2006, he earned a shot at welterweight superstar St-Pierre.
Serra was a 9/1 underdog and given next to no hope of beating GSP - who was coming off wins against legendary pair Matt Hughes and BJ Penn.
But in opening round the unthinkable happened as St-Pierre was caught with a shot and finished on the floor to seal a mammoth upset.
Sera's reign was short lived and in his first defence 12 months later GSP gained revenge to win in two round.
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The result changed St-Pierre's career forever, as he adopted a safer fighting style leading to more uneventful title defences, but he never tasted defeat again.