Deontay Wilder retired Chris Arreola after eight one-sided rounds in Alabama to stay WBC world heavyweight champion despite what appeared to be an injury to his right hand.
'The Bronze Bomber' (37-0-KO36) knocked his visitor down in the fourth with a heavy right and although he stated later a broken hand and pulled muscle had prevented him throwing the shot regularly thereafter, prompted Arreola's corner to pull their man out before the ninth.
Sporting a new 'frohawk' hairstyle, Wilder assumed the centre of the ring from the start, flicking out the jab with Arreola refusing to spend any time within range.
It was not until just before the bell that the Californian threw a shot - a missed jab - and he stared out from his stool intently before rising belatedly for the second session, during which he began to advance straight on to the Wilder jabs.
A cut on the inside of Arreola's eye socket opened before the end of that round and one-way traffic (albeit slow) continued into the third before Arreola attempted to hit back by lowering his sights to the body with momentary success.
As Arreola moved forward in an attempt to get himself into the fight, Wilder reeled off a trio of one-twos to stop the challenger in his tracks. The crowd responded with cries of 'Deontay' early in the fourth and their hero performed a bizarre gyrating dance on the ropes before finding his foe with a pair of uppercuts.
Wilder received a telling-off from the referee for his antics soon afterwards but he leapt into action towards the end of the fourth session as he felled Arreola with a solid straight right and accompanying flurry. The challenger rose and gamely made the bell under some more heavy weather.
The champion measured his man with hurtful jabs at the start of the fifth but was curiously economical with his use of the back hand as Arreola plodded forward grimly in an attempt to stem the tide with assaults of his own. Over the next few minutes of action, Wilder appeared to be happy to score points with the jab rather than attempt a finishing right.
The home fighter began to showboat again in the seventh as he mocked a trio of Arreola hooks in the corner before replying with some meaty shots that closed his opponent's left eye almost shut.
Wilder's reluctance to throw the right hand could have owed something to a nasty-looking graze down his right arm but his sharpness with the left was doing enough to mask the problem. The injuries to Arreola's were getting no better either, though, and he was deemed unfit to come out for the ninth.
There was entertainment - some of it bizarre - on the undercard, as Felix Diaz (18-1-KO8) upset the previously-unbeaten Sammy Vasquez Jr (21-1-KO15) with a unanimous points decision.
Having started well and looking comfortable at range, Vasquez Jr was flustered by Diaz's determined burrowing in the middle rounds; the underdog also displaying some of the technique that helped him to Olympic gold as he built up a decent lead.
Vasquez Jr rallied late on to an extent but was docked a point for consistently discarding his gumshield and when the scores were initially read out, Diaz and the arena were angered that the bout had been adjudged a majority draw. In a slightly farcical scene, the fighters were recalled to the ring and Diaz was declared the winner after a score correction.
Viewers were also treated to a first look of highly-rated young super-welterweight Erickson Lubin. The 20-year-old was always in charge of the durable Ivan Montero (20-2-KO8); moving to 16-0-KO11 with a clear-cut points success over eight.