The 2012 and 2008 Olympic 100m hurdles champions leave the world record-holder in their wake

Write Sally Pearson off at your peril.

The 30-year-old, who won 100m hurdles gold medals at the 2011 World Championships and 2012 Olympics, was too injured to run at Rio.

However, at the scene of her Olympic triumph, she won an exciting race in 12.59 to claim Australia’s first medal of the Championships.

American world record-holder Kendra Harrison had been lucky to make the final as a fastest loser after hitting a hurdle hard in her semi-final. Here, she had the best start and was ahead even though she slightly clipped the opening barrier but then she knocked the next three down and lost all momentum.

Pearson was now ahead and as the crowd roared she narrowly held her advantage to the line and mouthed the words “Oh my God,” repeatedly.

After the finish, she said: “I’ve worked so hard, I don’t know what has just happened out there. 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.

“I don’t know if it was surprise or what, but the emotion just escaped my body because I was so excited and so happy to have achieved what I have worked so hard for.

“I love this stadium, I love the people and I’m so happy to have been back here doing the same thing again. It’s a relief to be world champion.”

An even older Olympic champion – the 2008 winner Dawn Harper-Nelson – was only half a metre back.

Despite her season’s best-equalling 12.63 (from the semi-finals), she is only the seventh fastest American this year and was delighted with her best ever world championships at her fifth attempt.

It meant a repeat of the 2012 Olympics result where the American finished 0.02 back.

She said: “Me and Sally have just battled it out for years and it’s been so great to be here with her. Silver tastes like gold tonight.”

A metre back in third, in her first global final, Pamela Dutkiewicz was an equally pleased third in 12.72.

“I cannot believe it, I dreamed about this,” she said. “I was so focused and I pushed so much. It is crazy. There were so many big names in the field. And since I was a girl I have been admiring Sally Pearson.”

Harrison finished fast to take fourth, a thousandth of a second up on Christina Manning, both timing 12.74.

Belarus athlete Alina Talay was sixth in 12.81 with Nadine Visser matching her heptathlon position in seventh with 12.83.

Olympic silver medallist Nia Ali was eighth in 13.04.

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