All-Australian defender Sarah Allan doesn't have too many memories of the 2017 Grand Final between Adelaide and Brisbane.

One of the youngest players on the ground at 19, she was a second-string ruck who was in and out of the side, and even when named, was usually on the bench.

"I wasn't even sure if I was really going to be playing the Grand Final, so my build up was 'am I going to play, am I not going to play?' and then just being that younger player off the bench," Allan told womens.afl.

"I was just making sure that if I went on the field, I played my role. Looking back on that day, there's no specific moment I remember. It wasn't the greatest weather, but we got the job done and I just loved that feeling when the siren went."

Allan held onto her spot in the squad the following year, but lined up in a new position after an inspired move by her local coach at Salisbury during the 2017 AFLW off-season.

Having starred as a forward-midfielder in her junior career before a growth spurt pushed her into the ruck, Allan tried out the foreign defensive role at community level and thrived.

"I think Bec Goddard really liked that look, and they started training me there in the pre-season of 2018. We had a trial game and she said it was definitely the spot for me so from there, I haven't been able to get out of defence," she said.

"I've only really had four years' experience in defence. I think, at this level, I like knowing that I have a specific role to play. It eases my mind when I was sort of struggling with performance anxiety."

Allan described herself as a task-oriented player and enjoys playing defence because of its structure.

As she's grown in confidence in the role, she's been able to add more elements to her game, culminating in her recording the fourth-most disposals for Adelaide this year despite playing a key back role.

"In 2018, I feel like I was more of that stay-at-home full-back. Whereas when Matthew Clarke came in as a coach, he really encouraged us to work up the ground," Allan said.

"From there, that's where the intercept marking and actually getting the ball and working up the ground and getting to play a bit more offence has come into play. 

"I've really enjoyed evolving into that player that gets to move up because it's a bit more exciting than just staying at home at full-back."

Being stood down in 2020 from her role in Adelaide's community arm due to COVID-19 was a blessing in disguise, allowing the defender to work on her fitness.

"I was able to train a lot more and really focused on better nutrition and got a bit fitter. I tried to take some advice from Anne Hatchard, but couldn't quite get anywhere near her level of fitness and nutrition," she said with a laugh.

"I started to listen to players like that a bit more and came back to pre-season hitting PBs in the gym and getting a lot better at my fitness.

"I feel like that's put me in a position to be able to run around a lot more in the game and put myself in those positions where I can get more intercepts and work up the ground, but also continue to hone in on my defensive pressure as well."