"That was bloody hard".
"I was so exhausted".
Saturday's final was the latest instalment of the great rivalry between Pearson and Harper-Nelson, with the American having relegated the Australian into second spot at the 2008 Beijing Olympics, only for Pearson to reverse that result four years later in London.
She added: "I have no idea where my mum is sitting".
Pearson's winning time was actually slower than in her semifinal, in which she breezed to victory in a 12.53, though it seems unlikely that the two-time World champion will be too bothered as she capped off her return from injury with one of the sport's biggest prizes.
"Me and Sally have just battled it out for years and it's been so great to be here with her", said the 33-year-old Harper.
"My husband is in the crowd there somewhere, I'll try and find him and give him a hug soon".
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"I remember someone saying "you can be the world champion again" and I didn't feel awkward about that".
Harrison set the world record of 12.20 at the London Stadium a year ago, but only after missing out on the United States team for Rio, and suffered more disappointment here as she clipped hurdle after hurdle to come home fourth in 12.74.
"Silver tastes like gold tonight", she said.
"I am really excited to come out of this with a medal for the US". However, the American was overhauled by strong finishes from Harper-Nelson and Dutkiewicz (and eventually Harrison, who finished in fourth after a strong final two hurdles) though no one could get close to the Australian, who took the victory.
An overjoyed Pearson jumped up and down to celebrate her win - she was then picked up by the championships mascot Hero the Hedgehog and swung around before he carried her off round the track. "I'm so exhausted but I'm sure it will sink in soon", Pearson said.
"I've worked so hard, I don't know what has just happened out there".