Multi-weight world champion Pacquiao was expected to have few problems against the unheralded Horn on Sunday, but suffered a controversial loss at Brisbane's Suncorp Stadium as the Australian was declared the victor - and new WBO welterweight champion - by all three judges.
With scores of 117-111, 115-113 and 115-113 all in favor of hometown bet Horn, the boxing world was shaken by the result of the marquee fight in Brisbane, with many believing that Mr. Pacquiao did just enough to win by being more accurate with his punches and landing bigger blows than his opponent.
"I felt buzzed for sure, but I'm the Hornet - I've got to come back", Horn said.
Roach refused to condemn the judges who scored the fight in Horn's favour, adding: "I thought it was a pretty close fight". And while the decision to give Horn the victory over a clearly more dominant Pacquiao drew a huge amount of outcry from anyone who watched the fight, at least it got people talking about boxing for a few minutes on the national scene.
Pacquiao, one of the finest boxers of his generation, paid the price for a slow start and his inability to end the fight with a knockout.
And by then the world of boxing will know Jeff Horn.
The Australian responded by paying tribute to his rival, describing him as "an absolute warrior, a legend of the sport".
"But I came back in the 10th 11th and 12th". With Horn charging forward all day, he ducked down and it was nearly inevitable one of them would be opened.
Horn stuns Pacquiao in bloody battle
"It's 1000 per cent up to Manny whether he wants to fight again".
The people at ESPN who signed a deal with promoter Bob Arum for a series of Saturday night fights weren't crying foul afterward. "There's nothing anyone can say that will derail Jeff or I. We were both in the zone and we had a job to do".
'There's always naysayers saying I didn't win the fight.
Lonergan said he favoured a return to Brisbane, despite Melbourne's Etihad Stadium being mentioned as a possible alternate venue for Horn's next bout.
"I didn't see a lot there".
But Horn was awarded a contentious unanimous decision as the Filipino suffered the seventh defeat of an illustrious 68-fight career.
He was expected to overcome the unheralded Horn in an effort to entice Mayweather into a rematch of their super-fight, but the unbeaten Australian rose to the occasion in what was only his 18th fight in the paid ranks.