Liverpool's Darren Till suffered a shock loss to Jorge Masvidal in the main event at UFC London in front of a sold-out crowd at the O2 Arena.
The American veteran produced a devastating knockout in the second round to inflict only the second defeat of Till's UFC career.
Till, fighting for the first time since his title loss to Tyron Woodley in September, was heavily tipped to bounce back at the first time of asking and give himself another shot at the welterweight crown.
But, on a night that saw former champion Michael Bisping inducted into the UFC Hall of Fame, Till was dropped by a brutal left hand that will no doubt push him further down the pecking order for a fight against newly-crowned champion Kamaru Usman.
Masvidal said afterwards he has his own sights set on the title, but in another surprising twist he cut short his post-fight interview backstage to attack Birmingham fighter Leon Edwards - winner of the co-main event against Gunnar Nelson.
Returning to winning ways at the first attempt was always top of Till's agenda against the dangerous Masvidal, after suffering the first loss of his UFC career to Woodley in Dallas.
Till raised the roof on his last appearance in the UK in his home city of Liverpool, and was again buoyed by English support in the capital as he guided the crowd through a rendition of Sweet Caroline on his arrival in the octagon.
But the home favourite's relaxed demeanour only made the knockout more of a surprise.
Masvidal likes to play on the fact he loves "fighting in people's backyards" and insisted beforehand he would have to finish the bout inside the distance rather than let it go to the judges.
And he kept to his word to end his own run of successive defeats, as well as play up to his own tagline.
"I got dropped in the first and that made me wake up," said Masvidal after the fight. "I wanted to get him back immediately.
"I love the scrap - Darren is so tough. Before I dropped him I hit him with some bombs and the dude just smiled at me like, like I do to other people.
"The kid is headed far - he is going places for sure.
"I want to fight for the belt now. Darren only has one loss and that is to the champion. I've got a huge body of work in this division and this corporation. It's my time and I need that belt."
Till did not give any interviews after the fight, instead going to hospital for checks.
What next for Till?
The bout started in frantic fashion as Masvidal came leaping towards Till and caught the English fighter with a low kick, for which he apologised, but it seemed to rattle Till.
However the Liverpudlian responded with some showmanship of his own, shrugging off a couple of attempted strikes from his opponent before the knockout blow landed.
Till has spoken about the pain of his second-round loss to Woodley, but the welterweight division has moved on swiftly in the past six months and Till's position is now unclear.
Woodley has since lost the title to Usman and, with Woodley potentially set to face fellow American and former interim champion Colby Covington next, as the division's number three Till hoped to step up his campaign to face the Nigerian newly-crowned champion.
But now he may have to look elsewhere for his next fight on the promotion, with Edwards having a legitimate claim to face his fellow countryman after beating Iceland's Nelson in the co-main event, while UFC newcomer Ben Askren will also be waiting in the wings after attending the event as guest fighter and engaging in a Twitter spat with Till in the build-up.
Edwards makes it seven in a row
Birmingham fighter Edwards made no secret in the build-up to UFC London that he felt he should be fighting Till in the headline bout, but instead the number 10 welterweight was handed a co-main event fight against Nelson.
And he kept to his end of the bargain, taking a split-decision victory to extend his winning streak to seven fights - a run that stretches back to a loss to now-champion Usman in December 2015.
Edwards' improved grappling skills saw him match submission specialist Nelson, a team-mate of Irish star Conor McGregor, during the first round but support for his opponent - including the now-trademark Icelandic thunderclap - was deafening.
It was the Englishman who again ended round two on the attack as he pounced on a stumble from Nelson to throw a flurry of dangerous strikes on the ground which proved enough to clinch him the bout.
"I feel good, I'm on a seven-fight winning streak now in one of the hardest divisions in the sport," said Edwards.
"The winner of the main event, that should be my fight."
Like most people inside the O2, Edwards expected that to be Till, rather than Masvidal.
Masvidal and Edwards then came to blows as the American walked away from a post-fight interview, with the American throwing several punches towards the Englishman as Edwards was hauled away by his team.
The incident was swiftly dealt with by the UFC's security team.
Wood extends unbeaten start
Nathaniel Wood did not disappoint on his first UFC appearance in the UK as the bantamweight extended his unbeaten start to life on the promotion to three successive wins with a second-round submission against Mexican Jose Quinonez.
The 25-year-old Londoner had been eyeing a spot on this card since his UFC debut last June and the former Cage Warriors champion became a fans' favourite from the moment he stepped into the octagon at the O2 Arena.
'The Prospect', whose last trip to the venue was to watch his now mentor and trainer Brad 'One Punch' Pickett in action five years ago, was the more aggressive throughout and brought the entire crowd to its feet when he forced Quinonez to tap out with a rear-naked choke hold.
"This really means so much to me," said Wood. "It really is a dream come true."
Meanwhile, a "gutted" Danny Roberts felt his welterweight contest with London-based Claudio Silva should have been given longer after the referee stopped it for a verbal tap out in the third round.
"Yes, I might have made noise and grunted - I was hurt - but I was ready to take it all the way," said the English fighter.
Meanwhile, American Dominick Reyes took his light-heavyweight bout against Switzerland's Volkan Oezdemir on a split decision, before calling out UFC champion Jon Jones.
Marshman wins 'Battle of Wales'
The first fight on the main card was dubbed the 'Battle of Wales', but there was more than national pride at stake with the loser of the middleweight bout knowing their place in the UFC may also be under threat.
The respect between Jack Marshman and John Phillips was obvious - Phillips stopping to let his countryman to his feet in the first round before sharing a high-five - but when the result went in Marshman's favour by way of split decision it was greeted by boos from some inside the arena.
Phillips was left to shrug his shoulders in the direction of his corner, and ponder his future on the promotion.
There was no such reaction earlier when Molly McCann earned the first win of her UFC career.
'Meatball' said she "couldn't see" by the time her fight with Brazilian Priscilla Cachoeira was over, but despite the Liverpudlian's eye being completely swollen shut she took a unanimous decision after a brutal three rounds.
Mike Grundy began his career in the UFC with a bang as he stopped fellow Englishman Nad Narimani in the second round.