Anthony Joshua and Wladimir Klitschko served up a titanic heavyweight contest for the ages as the Briton climbed off the canvas to add the WBA title to his IBF belt at a sold-out Wembley.
England's national stadium was packed to 90,000 capacity as 2012 Olympic champion Joshua extended his perfect professional record to 19-0, but few anticipated the turbulent struggles he would have to endure to see off his esteemed 41-year-old foe.
After four cagey, exploratory rounds, the fight exploded into life in the fifth as Joshua clubbed Klitschko to the canvas.
The veteran's fourth stoppage loss of his career seemed imminent, but back he fired to stagger Joshua, before dropping him heavily in the sixth.
A surreal hush gripped the stadium as Klitschko looked to be jabbing his way towards the improbable, but Joshua drew on reserves not previously required in his career to separate the great Ukrainian from his senses with a chilling right uppercut in round 11.
The challenger tumbled to the canvas twice under ferocious assaults before referee David Fields saved him from his incredible gallantry.
Joshua called out his recently inactive domestic rival Tyson Fury in the ring afterwards, while motormouth American and WBC king Deontay Wilder represents another money-spinning option.
There may also be a rematch, but if this is Klitschko's last act between the ropes he can depart with his head held high.
He remains a two-time former champion, the division's dominant force for much of the past decade who was dethroned by Fury in November 2015.
A re-match fell through due to Fury's much-publicised struggles outside of the ring and Klitschko spoke repeatedly during the build-up to this bout of his "obsession" with winning back his titles.
After prolonged introductions, where Joshua stood on an airborne platform before his flaming initials and his adoring public, Klitschko – a challenger for the first time since 2006 – immediately sought centre-ring and popped out some left leads.
Joshua was looking for the left hook and the older man appeared skittish in his early fencing act, with nothing of real consequence landing inside the opening nine minutes.
Klitschko popped a pair of straight rights into Joshua's nose at the start of round four and a Joshua jab had him on his heels at the end of the session – pleasing action but no indication of what was about to unfold.
Joshua came out swinging, his left initially doing the damage before some thudding hooks had a groggy Klitschko down for a count. The champion presumptuously held his arms aloft and was soon startled by a wounded, proud warrior fighting for his career.
A clattering uppercut sapped Joshua, who was the man in need of the bell as euphoria inside Wembley evaporated into gasps. Worse was to follow for the Briton as Klitschko detonated a perfect right hand on his temple and he crumpled to the floor.
Joshua flew at Klitschko from the bell in round 10 and landed a crisp right to partisan roars, while the session ended with his foe crunching a brilliant short right to stop the 27-year-old in his tracks.
That was a fine punch but Joshua found something extra special to send Klitschko grimly unravelling to defeat in the next stanza.
The former heavyweight ruler tottered around, his legs deserting him as Joshua heaved left and rights until he fell. Klitschko was soon on the ropes again and had nowhere to go but the canvas after another right uppercut and left hook.
He was still under heavy fire after two minutes and 25 seconds of the round when Field decided he had seen enough and Wembley erupted.