Second-string lifter O screamed and then wept as he took a surprise gold with a 336kg total (151kg snatch/185kg clean and jerk) on Wednesday after North Korea's number one Kim Myong Hyok crashed out, failing all three attempts at his opening weight.
"I could not hold back the tears when I climbed on to the top step of the podium to receive the gold medal," an emotional O told AFP after he sobbed throughout the medal ceremony and national anthem at the JI Expo Arena in Jakarta.
"I was thinking of my motherland, first. But also especially my own mother, who always dreamed of me winning a gold medal in this competition," he added.
Still fighting to choke back the tears, he told reporters: "I will visit my mother's grave and give her this gold medal."
Doston Yokubov of Uzbekistan put in a consistent series of lifts to take advantage of the Korean lapses and secure silver with 331kg (145kg/186kg).
But there was a highly controversial bronze for Izzat Artykov of Kyrgyzstan with 330kg (147kg/183kg), competing in his first event since completing a two-year ban for testing positive for a banned stimulant at the Rio Olympics and being stripped of bronze there.
Local hero Triyatno, who like many Indonesians is known by only one name, failed with a final attempt at 186kg that would have given him silver and came fourth to huge groans of disappointment from a fervent home support.
- Snatch blowout -
The secretive nation's Kim had started as a heavy favourite but blew it straight away in the snatch to gasps from the large North and South Korean contingents in the capacity 2,000-strong crowd.
Kim's night was over quickly when he failed three times at his opening 150kg -- 10kg below his 2014 Asian Games record.
Kim, for such an accomplished lifter, never looked at ease, his eyes flickering nervously from side to side as he grasped the bar before crumpling on his final attempt.
It was a repeat of the stage fright that afflicted him in the 2016 Rio Olympics when he failed with all three clean and jerk attempts after lying in bronze medal place following a 157kg snatch.
It left the way clear for O, whose best previous result was silver at last year's Asian championships, to take the early lead with 151kg, from Artykov and Triyatno locked on 147kg and Yokubov 2kg further back.
Artykov was in his first competition since being testing positive for strychnine, better known as a deadly poison but in trace doses classed as a banned stimulant, and he only completed his two-year punishment for that offence on August 9.
South Korea's hope Won Jeongsik was never comfortable, tumbling dangerously backwards off the platform after collapsing in his failed last snatch attempt.
He eventually got to his feet and dusted himself down, but worse followed when he failed to register a lift in the clean and jerk and was also eliminated.