Before the largest indoor audience in boxing history (more than 78,000, breaking the previous mark of 63,350 set at Ali-Spinks II in September 1978), a methodical and composed Anthony Joshua, fighting most of the fight with a damaged nose caused by an accidental head butt, retained his WBA, IBO and IBF belts by scoring the fight's only knockdown (left hook in round four), cutting the challenger Carlos Takam over both eyes and landing a barrage of blows that prompted referee Phil Edwards to execute a curiously-timed intervention.
Joshua's offense was perfectly balanced in terms of output (227 jabs, 227 power shots), his jab was commanding (23.9 thrown/6.4 connects per round to Takam's 8.1/1.7) and his pace was measured (47.7 punches per round to Takam's 23.3).
The difference was Joshua's sharpness (33%-23% overall, 27%-21% jabs, 40%-25% power), which led to connect gaps of 152-52 overall, 61-16 jabs and 91-36 power, as well as his shot-for-shot power and his ability to string together that power. Joshua reached or exceeded 40% power accuracy in six of the final seven rounds while Takam reached that plateau just once in the entire fight (40% in round two).
The fight was Joshua's first since his epic 11-round tussle with Wladimir Klitschko in April, and just the second time he has been taken beyond seven rounds in his pro career.
Joshua has surpassed Mike Tyson's record of 19 consecutive knockouts.
"I was trying to break him down round by round," Joshua said.
"Unfortunately, the ref stopped it. I think people want to see Takam unconscious on the floor.
"That was where I was trying to get to. I don't have control over the ref's decision."
Takam (35-4-1) was fighting at 12 days' notice as an injury replacement.
Unbeaten champion Joshua opened up a nasty cut above 36-year Takam's right eye in the fourth round and knocked down the durable France-based Cameroonian late in round.
It was far from a straight-forward night for Joshua in the Principality Stadium as the 28-year-old appeared to suffer a broken nose in the second round after an accidental clash of heads.
Takam caught Joshua with some shot but they didn't have enough power to hurt the champion.