Veteran British heavyweight Audley Harrison was stopped in 70 seconds by unbeaten American prospect Deontay Wilder in Sheffield.
Harrison was stunned by a big right hand to the jaw - the first real punch thrown in anger by either man - and was sent to the floor when Wilder pinned him in the corner with a follow-up flurry.
Harrison, last seen winning Prizefighter in February, beat the count but referee Terry O'Connor had seen enough and waved off the contest - much to the British fighter's frustration.
The win improves 2008 Beijing Olympic bronze medalist Wilder's record to 28-0, while Harrison drops to 31-7 and will once again consider his future in the sport.
"It's going to be hard to come back from here," Harrison told Box Nation afterwards.
"I'm 41 years old and it won't be easy to get (more) opportunities... It is looking like it could be the end for me.
"It was terrible on my part. I was focused on training, felt great, comfortable and calm, then I got banged out.
"This will be a hard one for me to take. This is a tough night. It took a lot for me to get back to this position. It took fortitude and persistence. People aren't going to want to hear excuses and I understand that."
Also on the undercard of Amir Khan's fight against Julio Diaz, Gary Sykes made a successful defence of his English super-featherweight title.
Sykes earned a unanimous decision against Jon Kays to improve his record to 24-3.
The judges gave Sykes the verdict in the 10-round contest by margins of 97-94, 98-94 and 98-93.