Former All Black Williams (6-0) controversially emerged an unanimous points winner over South African legend Francois Botha (48-9) after his billed 12 round WBA international heavyweight title fight was for some reason cut short by two rounds - sparking howls from the packed crowd.
But the Brisbane faithful really sounded their disapproval after 27-year-old Sydney Roosters NRL star Williams was given the nod 97-91, 98-94 and 97-91 by judges despite appearing to have been trampled by the South African bruiser dubbed "the White Buffalo".
Botha, 44, showed all the experience that had earned him world title fights with boxing superstars Lennox Lewis, Mike Tyson and Evander Holyfield.
And he appeared to be following a 12-round plan to the letter by finishing strongly and battering Williams in the ninth round, only to appear stunned in the 10th when the ring announcer claimed the fight was reaching its climax.
When pressed after an angry Botha reluctantly retired to the dressing room, Williams' manager Khoder Nasser hinted that they cut it short after the big South African delivered several blows to the back of his prized charge's head.
Botha was disgusted by the verdict and claimed he would either protest the result or seek out a re-match.
"I was preparing for a 12-round fight and pacing myself," Botha told AAP.
"Then all of a sudden at the start of the 10th it was the final round.
"Then to top it off it wasn't even a full three minute round - it was 15 seconds short. My corner counted it.
"If he is not a coward he should fight me again. This is bullshit."
Williams had threatened to give up the sport if he was knocked out by Botha.
But it appears Williams' boxing options are limited despite somehow emerging triumphant from his "victory" over the hard-hitting Botha.
Williams still sounded content after the result was announced.
"I was happy with that. He caught me with a couple of shots at the end but I am proud of myself to have come out on top over someone with his experience," he said.
"Hopefully I gave the crowd their money's worth."
Earlier, power-punching Wallabies five-eighth Quade Cooper made a spectacular professional boxing debut by dropping Brisbane insurance agent Barry Dunnett in the first round of their cruiserweight bout.
Car crash assessor Dunnett (1-2 record) said ahead of his bout with Cooper that he wanted to step up for all frustrated pro fighters and end the "annoying" habit of footballers switching to boxing.
Dunnett tried to keep up his end of the bargain with a sparkling start to their fight, almost dropping Cooper in the first round in a sobering introduction for him to the sport.
However, Cooper bounced back magnificently to fell Dunnett with a stunning combination, ensuring the fight was all over within three minutes.
"I had so much fun it is hard to explain," the Queensland Reds playmaker said.
"A lot of time and effort came together.
"Barry has had a fair few fights and I won't lie I doubted whether I had what it took to get it done but I just had to trust my ability."