Anthony Joshua tasted a comprehensive points defeat to Oleksandr Usyk ending any hope of a historic showdown with Tyson Fury.
The pair were on course to determine the first undisputed champion since Lennox Lewis before Usyk ripped the script up and inflicted a second professional loss to Joshua.
This one was much different to the upset produced by Andy Ruiz Jr. This time the boxer with the better ring IQ and technical skills won.
Scores of 117-112, 116-112 and 115-113 were given after a near-masterclass from the unbeaten Usyk, who became only the third fighter after Evander Holyfield and David Haye to win world titles at cruiserweight and heavyweight.
Former world champions Lennox Lewis and Carl Frampton and Dillian Whyte, an ex-rival of Joshua's, questioned the Watford fighter's tactics but the man himself felt he was in the contest until round nine when a swollen right eye started to impede his vision.
Beaten, battered and bruised, Joshua put on a brave smile and as always, took defeat like a champion but the question is how does he avenge the defeat in the rematch?
It's a different rebuild to the dramatic defeat to Ruiz. This time, he will go back into battle with a much-improved fighter - a fighter who continues to get stronger in each fight as a heavyweight and won't go off partying and eating junk food.
It was only his third fight in the division - after sweeping up at cruiserweight - but make no mistake about it, he looked like the defending champion at the Tottenham Hotspur Stadium on Saturday night.
What Joshua said
"If it went well then it would have been perfect but it didn't so I can't really look at it and have any regrets," said Joshua, who disclosed he was unable to see out of a swollen right eye from round nine onwards in north London.
"What I'm happy about is I can go again and I've got a chance of becoming heavyweight champion of the world again. Only positives from here moving forward, I've had enough of looking at things from a negative point of view.
"I'm not a weak person. I'm not a sulker. I'm not going to go home (and) cry about it because this is war. It's a long process. This isn't just one fight and I'm done, I've got an opportunity to go back to the drawing board.
"I can't depend on anyone to pick me up and pat me on the back. That's why I'm not going to put my head in my palms and cry all night about it. I just want to get back to the gym and get back on the grind so I can improve.
"I'm going to lift myself up. I believe I'll get a good win in the next fight because of what I've learned in this fight. I'm a quick learner and we'll bounce back."
Change needed in team?
Trainer Rob McCracken has proved his worth as a world-class coach and cornerman. His work with Team GB at the 2020 Olympics saw them deliver the best performance by an amateur squad in the UK for more than 100 years.
His contribution on the professional circuit has seen Carl Froch retire on top of the super middleweight division and made Joshua a two-time unified heavyweight champion.
AJ is a loyal individual make no mistake about it. As well as signing a life-long deal with Eddie Hearn's Matchroom Boxing, he also continued to work alongside McCracken for the Ruiz rematch, instead opting to add to his coaching team rather than replacing him.
There is no suggestion that he will change now but something has to change if he wants to become a three-time world champion and it won't if he has the same approach going into the Usyk rematch.
Boxing Usyk at his own game was fatal. Being the bigger man in reach, size and punching power, Joshua will need to be the aggressor going into the second bout - a contest that will determine the Londoner's relevance in the heavyweight division.
In some ways, we still don't know what Joshua is - yes he's a superb athlete, but is he a slugger, a boxer or a mixture of both? It seems like even AJ is unsure of his style. Often looking gun shy and confused in front of Usyk, Joshua was unable to bully the smaller man, something Tyson Fury was able to showcase against a lighter Deontay Wilder in 2020.
The only real chance of him winning the rematch is by applying dirty tactics. Rough him up, force him into the ropes, clinch and land deadly uppercuts and hooks to the body.
A trainer who could inspire his comeback to glory is Eddy Reynoso - trainer of Saul 'Canelo' Alvarez, rising prospect Ryan Garcia and former opponent Ruiz.
The improvements made by Canelo since the first fight against Gennadiy Golovkin is obvious to see. The Mexican has since unified the middleweight and super middleweight divisions and became a four-division world champion with victory over Sergey Kovalev.
The key? Head movement, better footwork and not wasting punches. When he fought Billy Joe Saunders, he took to the centre of the ring, demanded his authority and his punching power saw him finish his opponent off inside seven rounds.
The jury is still out as to whether Reynoso can get Ruiz back on track - despite his return to winning ways against Chris Arreola - but he could be just the coach Joshua needs at this point of his career.