Whether he knew the building’s history or not, Brian Norman Jr. revisited it Saturday night with a stunning 10th-round knockout of favored Giovani Santillan to collect the WBO’s interim welterweight title.

Norman-Santillan took place at San Diego’s Pechanga Arena, where heavyweight Ken Norton stunningly broke Muhammad Ali’s jaw and upset Ali by split decision in 1973. 

Norman, 26-0 (20 KOs), likely broke Santillan’s nose and claimed the important triumph by delivering a sudden and smashing right uppercut that brought things to an end.

The WBO interim belt is of significant importance given that the primary WBO title belongs to undisputed champion Terence Crawford, who is poised to leave the division Aug. 3 when he meets WBA junior middleweight titleholder Israil Madrimov atop a stacked card in Los Angeles.

Santillan, 32-1 (17 KOs), immediately leaned into the hearty support of his historic hometown arena, but Georgia’s Norman embraced the road test and displayed an eagerness to engage.

Norman was willing to be rugged in the ring, and his ability to win some of the night’s earlier exchanges opened a cut above Santillan’s right eye.

Ringside broadcasters turned to Top Rank’s wise bank of Hall of Fame matchmakers — Brad Goodman and Bruce Trampler — with raised eyebrows, indicating the expected outcome in Santillan’s favor was in peril.

Indeed, it was.

The 32-year-old Santillan responded with a tack to press his quality foe to the ropes, subjecting him to withering inside combinations and hard left hands.

Norman’s pace slowed through the punishment, but he was only working to tweak his own attack.

In the eighth, a hard right hand shook Santillan’s knees like he was standing atop an active earthquake fault line.

The damage continued in the ninth, and Norman smiled at his cornermen, with one barking, “[Santillan] knows it’s over.”

The knockout came at one minute and 33 seconds of the 10th round.