Oleksandr Usyk ended Anthony Joshua's reign as world heavyweight champion with a unanimous points decision in London on Saturday.
Promoter Eddie Hearn warned on Wednesday the fight would prove Joshua's toughest ever test - and it was a test that proved insuperable for the Watford-born fighter.
The Ukrainian triumphed 117-112, 116-112 and 115-113 on the scorecards of the three judges in just the former undisputed cruiserweight world champion's third bout as a heavyweight.
The victory extended Usyk's perfect record as a professional to 19 wins from as many bouts, and scuppered immediate plans for Joshua to fight fellow British world champion Tyson Fury in a heavyweight unification bout.
Usyk's victory saw him become just the third boxer after Evander Holyfield of the United States and Britain's David Haye to win both the cruiserweight and heavyweight world titles.
From the opening bell the Briton appeared cowed by Usyk's slicker movement and sharper punches, a hesitancy bemoaned by fellow British heavyweight Dillian Whyte.
"I said if Joshua tried to box he was always going to lose. If he had to come out and bully him and push the pace and let his hands go he could have knocked him out in the first even round," Whyte told the BBC.
"But he came out and was being too negative he seemed like a gun shy fighter. You are the bigger man, have a go.
"I don't know, he lacked ambition in the ring there tonight.
"The first round, Usyk landed the first strong blow and Joshua was a negative fighter. He got tagged with a left and he was worried the whole time."
Nursing a heavily bruised eye and ego to match, Anthony Joshua beat a hasty retreat from the Tottenham Hotspur Stadium after the defeat, leaving the ring to the new champion who told Sky Sports the fight went as he "expected it to go".
"I had no objective to knock him out because my corner pushed me not to do that. In the beginning, I tried to hit him hard, but then I stuck to my job," he said.
"The only thing I wanted to do with this fight is to give praise to Jesus Christ.
"I have been working so hard since January in preparation for this fight, it took me half a year and I didn't see my family for so long. I missed seeing them playing. I want to go home and be happy with my family and I'm not thinking about the rematch."
If Joshua is to win the contracted rematch, he will have to radically alter his approach and throw far more punches and utilise his height and weight advantage.
In 2019 in Saudi Arabia the Briton successfully avenged his surprise defeat to the Mexican Andy Ruiz, but the immaculate Usyk is unlikely to be any easier second time of asking.