Now, the 31-year-old will become the most capped Wallaroos player when she runs out against New Zealand at Sunshine Coast Stadium on Saturday.
Leonard is primed to make a record 46th Test appearance, having debuted in 2019 and since representing her country at World Cups and Pacific Four Series.
But she's looking to the future and hoping to help steer the next generation of Australian rugby stars towards a home World Cup in 2029.
"My biggest hope through my time in the jersey, and hopefully my continued time in the jersey, is to continue to grow the game, share knowledge and leave the jersey in a better place than when I found it," she said on Thursday.
"I definitely didn't expect that I would ever happen to be in this position ... it's just a testament to the growth we've had in the game over the last few years.
"Back then (in 2019), when I made my debut, I was still trying to figure out what the laws of the game were and still finding my feet in the rugby space."
Leonard is part of the Wallaroos' rotated roster with Lily Bone, Brittany Merlo, Ashley Fernandez and Piper Simons returning to the 23, while Martha Fua replaces Faliki Pohiva (foot).
Teenager Waiaria Ellis earns a start at fullback as Faitala Moleka shifts to flyhalf.
Australia will look to end their Pacific Four Series on a high after defeats to the USA and Canada, but it will also be a final Test for interim coach Sam Needs after Rugby Australia confirmed they would appoint a new permanent head coach after the series.
"He's been able to ... drive that deeper level of connection, friendship and mateship through the team over the last few months," Leonard said.
"The future is really uncertain ... (but) as a player, we've definitely noticed the growth within the group."
Needs himself is focused on Saturday's clash, where the Wallaroos are heavy underdogs as they aim to beat their trans-Tasman rivals for the first time.
"A lot of the players over there (New Zealand) have been playing since they're eight, nine or 10, and a lot of our girls didn't start playing until they were in their late teenage years or early 20s," he said.
"We're really excited about the growth that we've had, and the girls are really pumped to be able to deliver a performance that they know they're capable of."
AUSTRALIA SQUAD TO MEET NEW ZEALAND:
Wallaroos: Brianna Hoy, Tania Naden, Eva Karpani, Michaela Leonard, Tiarah Minns, Kaitlan Leaney, Lily Bone, Siokapesi Palu Sekona, Samantha Wood, Faitala Moleka, Desiree Miller, Sidney Taylor, Georgina Friedrichs, Maya Stewart, Waiaria Ellis, Brittany Merlo, Martha Fua, Bridie O'Gorman, Ashley Fernandez, Piper Duck, Piper Simons, Ava Wereta, Nicole Ledington.
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