It's all about the little things: a millimetre this way or that, moisture content, the roll of the court, ball hardness and texture.

Jamieson Leeson wants Australians to know one thing about her sport of boccia: "It's not as easy as it looks."

"It looks like you're putting a ball on a ramp and rolling it down, but there are so many little factors that go into, you know, whether a ball rolls straight, whether it's the weather of the day, the humidity, the floor that the balls are rolling on," she said.

Leeson is partnering with Daniel Michel as Australia's two participants at the Paris Paralympics in boccia along with their respective ramp operators, Jasmine Haydon and Ash Maddern.

They're the number one pairing in the world having gone on a staggering run of 21-straight wins before the streak ended last year.

In 2023, the pair were named Team of the Year at the AIS Sport Performance Awards ahead of household names like the Australian women's hockey team, the Hockeyroos, and the national netball side, the Diamonds.

Michel is also the world number one ranked male player.

At the Tokyo Paralympics, he and his ramp operator, Maddern, made history, winning a bronze medal, Australia's first medal at the Games for 25 years.

Boccia is a sport for athletes in wheelchairs with severe physical impairments affecting all four limbs.

Leeson and Michel compete in the BC3 classification and use a ramp operator, who will follow instructions from the players to aim the ramp and then place the ball at a certain height, before the player tips it down the ramp and into play.

Michel does it with a pointer he holds in his mouth, while Leeson uses a pointer in her hands as she has movement from her elbows down.

For both athletes the sport has given them opportunities they never thought would be available to them.

Leeson grew up in the small New South Wales central west town of Dunedoo thinking there was no sport available to her.

"Growing up in the country, I didn't have access to any para sports," she said.

Once she discovered boccia, her world changed, but it was still a challenge with the closest available game a four-hour drive away in Sydney.

"Thankfully I had a dedicated mum that was able to bring me to Sydney every second week to learn more about the sport," she said.

"So, for me to finally be able to, you know, switch sides and be able to be on the court is, it's such a special feeling to represent everyone in my family in particular."

Michel has a similar story growing up in Sydney's south a "sport-mad kid".

"My earliest memories are playing modified footy in the backyard with my dad and brothers and always been a sports mad person, but I never found a sport that I could play," he said.

"I spent most of my childhood watching my brothers play, watching my friends play and just yearning for a way to get involved.

"And for whatever reason, never came across boccia until I was 15, and really stumbled across it, very luckily to a 'come try day'.

"And yeah, quickly saw that it was for me and realised there was apparently a big pathway, and for me that was really all I wanted: An opportunity to, to play a sport and to have that opportunity to, if I was good enough, go and play for my country at the highest level.

"And [I'm] just so grateful for the opportunities it has given me, I don't know where I'd be without it."

Watching Michel train with Maddern is an exercise in precision as he instructs her to make microscopic adjustments to his ramp.

Like lawn bowls, the object is to get your ball closer to the jack than your opponent.

Unlike bowls, the balls don't have a bias, but as Leeson stresses, they do not behave predictably.

The balls are made of plastic pellets encased in leather and vary in hardness and texture.

Leeson has about 60 balls she cycles through ranging from very hard to ones that are as soft as a bean bag.

"All my balls react differently; some err on turning left and some err on turning right," she said.

She said she'll spend up to an hour with each ball before competitions working out what is the best way to rotate it to get it to roll straight.

"No ball is ever perfectly round," she said.

But even then, other factors come into play: the court may have a bias and humidity will affect how the balls roll.

"You have a two-minute warm up at the start of the game," she said.

"That's where you have to figure out as best you can how the court is rolling.

"But you can move 20cm back and it might play completely differently."

And even then, the competitors only get to practice on one court out of eight that are used in competitions, and no two courts will perform in the same way.

Teams take turns to play six balls over four ends and the team with the most points at the end wins.

The players chose which ball to play depending on the state of the game and strategy.

Having a mathematical and geometrical mind helps.

"It's very mathematical for sure," said Michel.

"Angles, you know geometrical things and yeah, just simple arithmetic as well, it's quite a 'mathy' game.

Leeson agrees.

"Oh, I mean, absolutely. I mean, I'm studying statistics at university, I think that says enough," she said.

They're helped by what Leeson calls her cheat sheets: tables of numbers that show how far each ball will roll when placed at a certain height on the ramp.

The numbers range from 0 at the bottom up to 22 at the top, and so using their tables the players can determine where to place the ball.

"Then we have another sheet which is like a grid map which tells me if a ball is half a metre from the backline and a metre where it is in relation to my box," Leeson said.

Each ramp has three small marks which the players use to aim.

Michel explains how he uses them: "The centre line sort of is what you wanna aim up for.

"So that gives you where your line is and then the wider two lines, that's sort of like… about the width of the ball.

"So, if you're trying to fit through a gap or something, you can judge how much you need to give for that ball to get through the gap," he said.

If it sounds like a game of absolute precision, it is, but the variables are what gives boccia its charm.

Fundamentally, it is unpredictable.

Said Leeson: "I could roll my best ball 10 times down a ramp and it would only go to the same spot three times.

"The variability definitely adds more of a challenge to the sport, and I don't think it would be as much fun if it was uniform.

"The skill is being adaptable to how the balls are turning, different environments overseas and different opponents.

Now, the challenge is to put those skills into practice when the two compete at the Paralympics in Paris.

They're both Paralympic veterans: Michel will be going to his third Games and aiming to better the bronze he won in Tokyo in the singles, while Leeson will be at her second Games.

But Paris will be the best chance of doing better as individuals and as a team in the pairs after they finished fifth at Tokyo.

And both are grateful for what the sport has given them.