Lauren Parker glanced behind her, smiled, and allowed the tears to flow as she rolled across the line.

Three years after being pipped to a gold medal in Tokyo by about a second by American Kendall Gretsch, Parker blew the entire field away with a dominant performance to clinch a golden redemption.

Poor water quality in the River Seine had postponed the triathlon event by 24 hours.

A training accident in the build-up had also threatened to derail her.

None of that mattered for Parker. 

What's another 24 hours when the pain of that agonising defeat had dogged her for the past three years?

What's a training crash, however "nightmare-like", compared to the U-turn her life went through in 2017, when she crashed into a guardrail at 45 kilometres per hour?

Because once the racing got underway in Paris, she proved that she had waited long enough.

"I can't believe it. A dream come true today," Parker told Channel Nine.

"I've been through a lot in the last three years and it just sums up everything I've been through and worked hard towards.

"Every single session I've been putting myself through in training, I've had that vision and I can't believe I've done that today."

The 35-year-old's victory sealed Australia's seventh gold medal of the 2024 Games. 

Parker opened up a big lead on the first leg — a 750m swim through the Seine — exiting the water with a 52-second advantage.

Gretsch — who started 3 minutes and 38 seconds after Parker on account of her being a PTWC2 athlete, while Parker is PTWC1 — was third out of the water.

Given her stunning chase in Tokyo, her presence, however distant, was still ominous.

Three years prior, the American chased down Parker on the hand cycle and wheelchair legs to steal an extraordinary gold medal and was going about doing so again in Paris, with the Eiffel Tower looming large on the horizon.

Gretsch moved up into second during the five-lap 20km hand cycle leg, gradually hauling Parker in across the Parisian cobbles.

Still, the Australian was 1 minute and 58 seconds ahead of her American rival after the pair both transitioned into the 5km wheelchair phase of the competition. 

Gretsch continued to eat into Parker's lead, but she was always going to run out of road.

Parker smiled a grin of pure relief as she crossed Pont Alexandre III, bursting into tears as she lowered her head and crossed the line alone.

"It means everything. I've been through so much since then (her 2017 accident) as well," Parker said. 

"The emotional rollercoaster I've been through, pushing through every single day, every single second just to be here.

"I couldn't be happier today."

The American took silver, 1 minute and 23 seconds behind, with Canada's Leanne Taylor claiming bronze. 

Meanwhile, in the men's PTWC triathlon, Australia's Nic Beveridge finished sixth.