British heavyweight Anthony Joshua was dropped and stopped on his American debut versus replacement Andy Ruiz Jr.
Making a tentative start, Joshua was exposed as the 2012 Olympic champion failed to make an impression at Madison Square Garden.
Joshua put Ruiz down, as expected in the third, before backtracking and suffering his own crisis at the New York venue.
A massive underdog, Ruiz looked assured compared to the four-belt heavyweight champion, picking his moments until the end.
That fate came in the seventh round. Joshua was shaken for the third time in the fight as Ruiz pushed towards unified title status.
Looking completely useless, Joshua was stopped on his feet as a shocked crowd watched on in awe.
Fights with Deontay Wilder and Tyson Fury, both of whom had predicted the outcome, are now pie in the sky for the 30 year-old.
A rematch is on the cards. Although the way Joshua looked, Ruiz could certainly repeat the job in the second contest.
On the undercard, Callum Smith defended his super-middleweight strap. Whilst Katie Taylor unified the lightweight division fully against Delfine Persoon.
Josh Kelly drew with Ray Robinson on what was a bad night all round for promoter Hearn.
12-Round Heavyweight Championship Bout
Andy Ruiz, Jr. (33-1, 22 KOs) defeats Anthony Joshua (22-1, 21 KOs) by TKO at 1:27 of Round 7.
12-Round WBA Super World Middleweight Title Bout @ 168 lbs.
Callum Smith (26-0, 19 KOs) defeats Hassan N’Dam (37-4, 21 KOs) by TKO at 2:56 of Round 3.
10-Round Female Lightweight Unification Title Bout @ 135 lbs.
Katie Taylor (14-0, 6 KOs) defeats Delfine Persoon (43-2, 18 KOs) by majority decision.
Scores: (95-95, 96-94 x2)
10-Round WBA International Welterweight Title Bout @ 147 lbs.
Josh Kelly (9-0-1, 6 KOs) and Ray Robinson (24-3-2, 12 KOs) fought to a majority draw.
Scores: (96-95 [Kelly], 95-95, 95-95)
10- Round Light Heavyweight Bout @ 175 lbs.
Joshua Buatsi (11-0, 9 KOs) defeats Marco Antonio Periban (25-5-1, 16 KOs) by TKO at 1:39 of Round 4.
10–Round Vacant WBO International Super Lightweight Title Bout @ 140 lbs.
Chris Algieri (24-3, 9 KOs) defeats Tommy Coyle (25-5, 12 KOs) by TKO in Round 8.