From the moment she qualified for her first Olympic Games as a 16-year-old high school student, Sydney McLaughlin-Levrone has never paid much attention to conventional wisdom.
For more than three decades since Soviet hurdler Marina Stepanova became the first woman to run the 400m hurdles in under 53 seconds in 1986, the athletics world had wondered when, or if, the 52-second barrier would be broken.
Yet in the space of a few seasons, McLaughlin-Levrone has obliterated that longstanding benchmark, redefining notions of what was possible in her event.
In 2021 she clocked a world record 51.90sec at the US Olympic trials in Eugene, Oregon, to become the first woman under the 52-second mark.
She followed that up by shaving a massive 0.44sec off her own record when she stormed to victory at the Tokyo Olympics in 51.46sec.
In 2022, she bettered that mark at the US trials in Eugene with a time of 51.41sec, before clocking a jaw-dropping time of 50.68sec on her way to victory at the World Championships a month later.
After dabbling with the flat 400m in 2023, McLaughlin-Levrone returned to her specialist event this season and has once again returned to her record-breaking ways.
She booked her place in Paris with another world record at the US Olympic trials last month, storming home in 50.65sec with a performance that appeared to take even herself by surprise.
"I was not expecting that," McLaughlin-Levrone said after her victory in Eugene. "I'm just amazed, baffled and shocked."
It was the sort of performance that suggests McLaughlin-Levrone is more than ready to make more history in Paris, where she could become the first woman ever to successfully defend the 400m hurdles title with a victory.
She is likely to face a stiff challenge in the form of the Netherlands' Femke Bol, who won gold at last year's world championships in Budapest in the absence of the injured American and has just become only the second woman to break the 51-second barrier for the event.
UNBEATEN STREAK
But McLaughlin-Levrone has demonstrated she's rarely more dangerous than when pushed by a competitor, citing her early career rivalry with 2016 Olympic champion Dalilah Muhammad as helping push her to new heights, a case of "iron sharpening iron" as she describes it.
Few would bet against McLaughlin-Levrone retaining her Olympic crown at the Stade de France on August 8, a day after she turns 25.
As well as her Olympic title, McLaughlin-Levrone will also be defending a five-year unbeaten streak in her event. Her last defeat over the 400m hurdles came in the final of the 2019 World Championships in Doha, where she was pipped for victory by her compatriot Muhammad.
Born in New Jersey in 1999, track and field was embedded in McLaughlin-Levrone's DNA.
Her father, Willie McLaughlin, reached the semifinals in the 400m at the US trials for the 1984 Olympics, while her mother Mary was a respectable half-miler.
As a young girl, McLaughlin-Levrone watched the 2008 Beijing Olympics, and her idol Allyson Felix, and determined that she would one day perform on the same stage.
After qualifying for her first Olympics as a teenager in 2016, McLaughlin-Levrone's progression continued steadily before her breakthrough Olympic crown in 2021, her improvements coming rapidly after linking up with new coach Bobby Kersee in 2020.
In Tokyo, she added another gold medal after forming part of the relay 4x400m relay squad, where she raced in a quartet alongside Felix.
"Since I was eight years old, that's something I had aspired to do, and for it to finally come to fruition felt like a weight off my shoulders," McLaughlin-Levrone said of her 2021 gold.
Victory in Paris would raise the prospect of McLaughlin-Levrone targeting a third straight Olympic gold at the 2028 Los Angeles Games.
While Los Angeles remains a long way distant, McLaughlin-Levrone says she sees herself running well beyond this summer's Olympics.
"It does get harder as the years go by," she said in an interview with Women's Health magazine.
"You're pushing your body to its limits. It's a part of sports that can be physically draining, mentally draining, and that's why taking breaks and remembering why you love it is so important.
"Track is not going to last forever, so I'm trying to continue to enjoy it. I don't want to take anything for granted."