Kendra Harrison laid down a marker that she is in the form to at last win a major title, blitzing to a world-leading time of 12.24sec in her 100m hurdles heat in the World Athletics Championships in Budapest on Tuesday.

Harrison's performance will not have gone unnoticed by her rivals especially the woman who replaced her as world record holder, defending champion Tobi Amusan.

The Nigerian only got the green light to compete in the championships last week after being cleared over an alleged breaking of the dope-testing whereabouts rule.

The 26-year-old, though, eased into Wednesday's semi-finals winning her heat in a leisurely 12.48sec, beating Olympic bronze medallist Megan Tapper of Jamaica.

"I'm just thankful I'm here in Budapest and able to race, using my talent," said Amusan.

"It is not been the best but I'm here.

"I tried to stay as relaxed as possible (through all the uncertainty) and do what my coach tells me. So here I am." 

Harrison was the one who took the eye as she bids to turn two silvers (the delayed Tokyo Olympics in 2021, 2019 world championships) into gold.

The 30-year-old American's time was just three hundredths of a second outside her personal best, which was when she broke the world record in London in 2016.

"I am truly happy about this run," said Harrison.

"I do not really know how I did it, I was kind of blurred.

"I did not know how fast I was ready to go but he (her coach) just told me to be aggressive every single round, to give everything I have."

On her coattails came Devynne Charlton in a new Bahamas record, while third and fourth-placed Danielle Williams of Jamaica and Britain's Cindy Sember ran season's bests.

- 'Game of survival' -

Harrison's former training partner, Olympic champion Jasmine Camacho-Quinn, coasted through, the Puerto Rican timing 12.50sec.

Camacho-Quinn shrugged off Harrison's astonishing time and appeared to be more concerned by the heat which she said was "annoying".

"I do not need to do my best in the first round," said the 27-year-old.

"I knew what I had to do to win that leg."

The 2019 world champion Nia Ali began her campaign to regain her crown in impressive fashion producing a faultless display to time 12.55sec. 

The 34-year-old breathed a sigh of relief at coming through as the defence of her title ended in the heats in Eugene last year when she fell.

"That was a tough one, the hardest round for me because of what happened last year," said Ali, who had the fastest time in the world this year until Harrison's stunning run.

"My last few races have gone really well, but you never know as it is a game of survival.

"I stayed focused, I did not want to try anything crazy.

"I came to Budapest prepared, now I just need to prove it.

"I hope my body will agree with me."

Jamaica's young hope Ackera Nugent showed no nerves whatsoever in her first senior global championships, the world Under-20 champion coasting home in 12.60sec to win her heat.

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