Impossible does not really exist.

It is the mantra driving Australian swimmer Lakeisha Patterson as she vies for her fourth Paralympic gold medal in Paris.

Guided by long-time coach Harley Connolly, Patterson will be out to defend her S9 400 metres freestyle title when she takes to the pool for her third Games appearance.

The 25-year-old has had a chokehold on the race since she set a world record at the 2016 Rio Paralympics to earn her first gold in the S8 category.

Patterson had shaved 0.11 seconds off the previous record set by America's Jessica Long to post a time of four minutes and 40.33 seconds.

She again came home with gold from the Tokyo Games in 2021 as an S9 swimmer after being reclassified.

Ahead of the Paris Games, Patterson admits to nerves despite her experience.

But she points to an ethos set by Connolly that has influenced her preparations.

"Harley's coaching me into my third Paralympic Games now together so that's a pretty long time working alongside one another," said Patterson, who also won a relay gold in Rio.

"He was the first person that taught me 'impossible doesn't really exist' and it's up to us to create the destiny that we want.

"It's tough. No day is ever easy and presents its own challenges, but we're definitely a team.

"At the end of the day, behind those blocks, it's not just me racing for that elusive gold medal."

Patterson will also be competing in the S9 100m freestyle and the SM9 200m individual medley in Paris.

"You still definitely get the butterflies in your stomach," she said.

"It's just not allowing the pressure to get to you but knowing that everyone is with you no matter the result.

"I'm going out there to do my best for my country, for my coach, for my family, for my friends, but mostly for myself.

"And I know that no matter the result, my success does not define me. I am who I am.

"I'm also Lakeisha Patterson and then Lakeisha Patterson the swimmer."

The Paralympics run from August 29 to September 8, Australian time.

AAP