The 22-year-old will need to pass strict concussion protocols in order to prove her fitness for Saturday's opening match against England in Canberra after copping a ball to the back of the head in nets.

Gardner had turned and was walking away when she was struck with a ball at the base of her head on Sunday, and showed symptoms of a concussion soon after, including a headache.

The Sydney Sixers star has had a history of concussions including multiple over the past few years from incidents in both matches and in the nets and has spent several weeks on the sidelines with the injury.

"It's not ideal," said Australian skipper Meg Lanning as the team begins preparations for the T20 World Cup next month.

"She was a little bit unlucky (on Sunday), she probably wasn't paying as much attention as she should have been unfortunately. But she's OK. We're just sort of being precautionary with her and making sure she's OK.

"There's steps that she'll need to go through to be fit for Saturday and she'll make sure that she's ready to go."

Given her history, Gardner will undergo light training sessions every second day, but she will need to show no symptoms in the 24 hours after each session in order to progress, as per protocol.

Gardner has previously spoken about her concerns with frequent concussions, saying she feels delayed symptoms with onset of headaches and nausea the day after contact.

Tayla Vlaeminck and Erin Burns were also sidelined for Monday's warm up match against CAXI at Sydney Showgrounds along with Gardner.

Vlaeminck has returned to full training and is expected to be fit for Saturday's match, which serves as preparation for the T20 World Cup next month.

Australian Associated Press