The lightning-fast girl with a sick heart who grew up to be a footy champion.

Growing up, all Kate McCarthy wanted to be was the first female Brisbane Broncos player.

It was a big dream for a little girl obsessed with the male-dominated game of rugby league, especially one with a serious heart condition.

A post shared by Kate McCarthy (@kate.mac__) on Sep 26, 2013 at 3:50pm PDT

McCarthy was just 10 years old when she was fitted with a pacemaker for a stage-three chest blockage that was causing her to have seizures, sometimes up to seven times a day.

Doctors weren’t sure if she would ever play sport, especially high contact sport, but boy, did she show them.

Not sure what we’re talking about? Here’s what went down in AFL Women’s last weekend. (Post continues after audio.)

The lightning-fast 23-year-old, who has played touch footy for Australia and cricket for Queensland, is now an AFLW star on the rise.

“My mum gets a little bit worried if I ever get tackled,” McCarthy told Mamamia.

“She gets a little bit worried and checks if I come out of it OK, my dad too. I reckon they get a lot more worried about than I do.”

The Brisbane Lions midfielder left her Collingwood opponents struggling for breath on Saturday afternoon when she sprinted from the centre to the goal square, bounced the ball five times and booted the goal of the season so far.

Seriously, talk about a pacemaker.

The Lions are now three from three and on top of the ladder. Meanwhile, McCarthy is on top of the world after kicking two in front of a packed home crowd, which included her parents and her “number one fan”, her big sister Emma.

The secondary school teacher has even been getting props for her weekend performances in the courtyard.

“[The students] have been so supportive me. I get to school on a Monday and heaps of them come up to me and say, ‘That was such a good goal, Miss’,” she said.

“Kids who don’t like AFL have even been following to see what I’m up to.”

A post shared by Kate McCarthy (@kate.mac__) on Dec 9, 2016 at 6:34pm PST

McCarthy first gave Aussie Rules a whirl as a way to improve her fitness, but “absolutely fell in love” with the physicality and the camaraderie she found in the game.

“After one training session I was hooked, and I haven’t stopped playing since,” she said.

Now that the national women’s competition is finally a reality, she’s hoping it will prove to other sport-loving girls they’re “as capable as any man”.

A post shared by Kate McCarthy (@kate.mac__) on Feb 18, 2017 at 9:21pm PST

“There’s a club right across the road from us at school and I have students approaching me and asking about getting a girls team up and running,” she said.

“If that could come from what we’re for doing, that would be amazing.

“Whatever catches their eye, whether footy or something else, they should follow whatever they want to do and not let anyone tell them otherwise.”