A world record that has stood for 28 years has finally been smashed — by a woman who couldn’t make her country’s Olympic team.

Sally Pearson’s keen American rival Kendra Harrison streeted the field in the 100m hurdles at the London Anniversary Games to clock a stunning 12.20s, one hundredth of a second quicker than the world record set back in 1988 by Bulgarian Yordanko Donkova — five years before Harrison was born.

Harrison missed US Olympic team selection for Rio when she finished sixth in the cutthroat trials earlier this month.

Instead the three women who will wear the stars and stripes in Rio were nearly three strides behind Harrison in the London race.

“To hear people call me a world record holder, it sounds remarkable,’’ said Harrison.

“I wanted to come out here and show the world that I still have it even though I won’t be going to the Olympics. I had to give it all I had.’’

Originally the timing recorded the race as 12.5s, which Harrison said she was happy enough with, before the correct time was flashed on the big screen.

The 23-year-old said: “I was so happy when it came up and I was feeling really blessed. It shows that even if you don’t go out there and make the team, you have to keep going and be strong. I just ran my best and look what happened.’’

Kendra Harrison reacts with shock after realising she’s broken the world record. Pic: AFP

Pearson had withdrawn from the Australian Olympic team because of persistent injuries but her time away from the intense competition has shown that her rivals have taken the event to a new level.

Harrison’s performance overshadowed the headline act, Usain Bolt, who ran 19.89s in his first 200m in nearly a year. He looked supremely comfortable for his stated aim to break his own world record of 19.19s at the Rio Olympics.

Bolt, who remains undefeated in the Olympic stadium in East London, is confident he can iron out any glitches with his cornering in his favourite discipline.

“I’m getting there. I am not fully in shape,” said the 29-year-old. “I need more work, but over time I will get there. I thought the cornering wasn’t perfect. But I am feeling good.

“At least I came here, ran the race and had no injuries. I am ready to defend my Olympic titles. The main thing is I am injury free. I always love competing here. It’s always a great fun at this stadium.”

Usain Bolt poses after his win. Pic: AP

At the same meet Australian 1500m runner Linden Hall clocked her second fastest time of 4min.03.89 to finish eighth; javelin thrower Hamish Peacock picked up a bronze medal with a throw of 82.94m, Lauren Wells was seventh in her 400m hurdles in 55.37s and Eleanor Patterson was sixth in the high jump with 1.92m.