After two years of injuries and numerous obstacles, the 30-year-old had stared down the world record holder and won her second world 100m hurdles title. Since former champion Dawn Harper Nelson (season best 12.63) won the heat, the Americans have four in the final and could sweep the medals again - like they did a year ago at the Rio de Janeiro Olympics.
Pearson crossed the finish line, looked to her right and saw Harper-Nelson was barely behind.
"When I knew I felt that I knew it was in me to do it".
"I was so exhausted".
She missed the last two seasons due to hamstring and Achilles injuries and a badly broken wrist and feared for her career. Doctors described the injury as a "bone explosion".
"It's been a long journey back from injury, but to get this moment and go and celebrate in front of my family is unreal".
"My husband (school sweetheart Kieran) is in the crowd there somewhere, I'll try and find him and give him a hug soon".
The 30-year-old - the 2011 world champion - missed both the 2015 world championships and 2016 Olympics because of serious injuries, losing out on the former after suffering a "bone explosion" in her wrist in a bad fall at a meet.
Defending champion Danielle Williams of Jamaica failed to make the final while last year's Olympic champion Brianna Rollins, who led an American sweep of the Rio podium, is banned for a doping violation.
She then underlined that by reaching the final as the fastest qualifier in 12.53 on Friday.
After contemplating hanging up the spikes, the 30-year-old qualified fastest for the final and held her nerve to add to her triumph at the 2011 world championships.
"On the first day of athletics at the Olympics I chose to coach myself", she said. It was like Beijing in 2008 (she won a surprise Olympic silver) when I didn't come in as one of the favourites. She has been doing it more than long enough.
"She has got the determination that whatever she sets her mind to she is going to do it and she is going to do it properly".
She controlled the race from there, winning in 12.59 seconds ahead of long-time rival Dawn-Harper Nelson (12.63).
Harper Nelson admitted she wasn't surprised to look across on the finish line and see that it was the Australian who'd denied her the gold medal. I don't think I would be here without their support.
Pearson thanked her close inner-circle for getting her across the line.
"From the first day I started training (in August 2016) I knew it was possible, I knew I could get here", she said.
"Toward the end, I could see Sally out of the corner of my eye".
"They expect me to be winning all the time but I'm pleased to be in my first world final and have learned a lot".
It was a third major 100m hurdles title for Pearson, who had previously won gold at the 2011 world championships in Daegu and the 2012 London Olympics.
Pearson and 400m hurdler Jana Pittman are the only two Australian track and field athletes to have won individual world golds.
Her next challenge will be winning a third successive Commonwealth title on home soil on the Gold Coast next year.