CHELSEA Biddell is the quiet achiever of Adelaide's star-studded line-up.

The 25-year-old played 10 games as a key forward across the 2020-21 seasons, kicking four goals in that time.

But things started to change at the start of 2022, thrown into defence to learn under the tutelage of Sarah Allan and teammate-turned-backline-coach Marijana Rajcic.

By the second season of 2022, she was an All-Australian key back, and without three senior players around this year (Allan and Najwa Allen with hamstring injuries, Rajcic now coaching), it's been on Biddell to lead an incredibly young defence.

Zoe Prowse (20 years old) has come on in leaps and bounds, Sarah Goodwin (19) has slotted in after moving from Port Adelaide, Kiera Mueller (20) is only in her second season and Brooke Tonon (20) in her third.

The versatile Stevie-Lee Thompson has spent parts of the season in defence, but missed the past two weeks with back spasms, while Maddi Newman floats in and out, spending most of her time on the wing.

"It's been tough without (Allan). She taught me everything I know, so it sucks not having her out there. She's obviously an incredible leader and an incredible player," Biddell told afl.com.au.

"It's hard without her, but we've got some brilliant young talent coming through, who have really stood up this season, and it's been really exciting.

"I'm probably unintentionally taking on a leadership role. My communication has become even more important without the voice of Sarah Allan and Naj, so I've stepped into that role a little bit. It's been a good, new challenge."

Biddell's rise has been fairly rapid even by AFLW standards, named All-Australian in her sixth year of playing any form of football.

Now-Crows teammate and schoolmate Rachelle Martin was keen to give football a go, convincing Biddell (along with Martin's older sister Hannah Button) to join her at West Adelaide in the SANFL.

"I played a bit of basketball and netball in my youth, more so basketball. I made the transition when I was about 18 and never really looked back," she said.

"Going into defence was a pretty big change, I was drafted as a forward. So that was a huge positional switch for me. From there, it was just about building confidence, and slowly, game-by-game, I was able to work my way into games and play more consistent footy, which was my aim.

"Maybe I've gained a little bit of confidence from the All-Australian. It was obviously a huge honour, but for me, it's just about playing my role for the team and doing my bit. We pride ourselves on team defence, so the more I'm able to play my role in that regard, it's good."

Adelaide is one of two undefeated sides halfway through the season and will meet top-of-the-ladder Melbourne on Saturday afternoon at Casey Fields.

While the Crows have been perennial finalists, winning flags in 2017, 2019 and 2022 (season six), Biddell feels they're in better form than last season's preliminary finalist squad.

"I feel like we're using our run a bit more, and we're playing more exciting footy," she said.

"Last year, we were a bit straight up and down the lines. We've been able to (switch) and break lines a bit and use our run and carry a bit more this year, which has been great."