Six years after her first world title in the event, Sally Pearson struck gold once again as she won the 100-meter hurdles title at the World Athletics Championships in the same stadium where she won the Olympic title five years ago.
Harrison, the favorite coming in, disappointed and ended up in fourth in a time of 12.74 and is still without a global outdoor medal.
Farah, who won the 10,000m once again last weekend, dug in to finish 0.43secs behind new world champion Edris, while Paul Chelimo of the United States claimed bronze.
World record holder Kendra Harrison disappointed in finishing only fourth confirming that her Achilles heel is a lack of championship experience having failed to make the Olympic team a year ago.
Pearson broke her wrist in 2015 and missed the 2016 Olympic Games with achilles and hamstring injuries.
"I don't know if it was surprise or what", said Pearson of her exuberant celebration.
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Back in London, and back fit and firing, Pearson flew out of the blocks and held off Dawn Harper-Nelson to take the title.
Pearson split acrimoniously from her longtime coach Sharon Hannan after finishing second behind Brianna Rollins at the 2013 world titles.
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.
Pearson, whose English mother brought her up as a single parent and in very straitened circumstances, taking two jobs so her daughter could realise her dream, said it had been a long and hard road back to the top.
"Silver tastes like gold tonight".
"I've worked so hard, I don't know what has just happened out there".