WHEN on the field, Tiarna Ernst (pictured above) is a fierce defender for the Western Bulldogs. Off the field, though, she's been helping an opposition player who happens to be one of the biggest names in the competition.

Melbourne superstar Daisy Pearce gave birth to twins more than a fortnight ago and Ernst, who is an obstetrician, helped the Demon through her pregnancy. 

The pair used to work together at Box Hill Hospital, where Pearce was a midwife, hence their connection.

Ernst missed the birth of Sylvie and Roy, although she had a pretty good reason. 

"I was fortunate enough to be a little bit involved in Daisy's care for her pregnancy, so I've been involved behind-the-scenes and knowing what's been going on the last couple of weeks," Ernst said.

"Unfortunately, I missed the delivery. We were in Launceston playing North Melbourne at the time but I visited her shortly afterwards in hospital."

Melbourne co-captain Elise O'Dea visited Pearce and her kids last week and was not surprised to see the superstar excelling at her new role. 

"They're probably the two cutest babies I've ever seen and they're very well-behaved. Daisy's nailing it, of course, in terms of motherhood, and her partner Ben's doing a great job," O'Dea said. 

FULL FIXTURE Check out when and where your club plays

Ernst and O'Dea were speaking on Wednesday morning at Marvel Stadium, alongside star North Melbourne defender Jess Duffin and Collingwood's Ash Brazill (pictured above), ahead of Saturday's double-header at the venue. 

Collingwood and North Melbourne will clash first from 4.40pm AEDT, before the Bulldogs and Demons meet at 7.10pm AEDT.

The double-header ‘home’ teams, the Magpies and Dogs, will wear specially designed Marvel-themed tops in the warm-up.

Despite the Pies being winless and facing a North side smarting from its first-ever AFLW loss, Brazill believes her side can win.

"We've got nothing to lose now, so hopefully that gives the girls a bit of confidence, just to go in and play some good football," Brazill said.

RACE FOR FINALS Where is your team placed?

She implored her teammates to keep cool. 

"(We've been) trying to get it on the boot and kick it as far as we can and I think (our improvement) showed last week (against Carlton) – we hit targets, we were calm under pressure and we were able to get it our forward 50 and kick some goals," Brazill said. 

"We just need to not freak out when we have the ball." 

It's a lesson Duffin wants her side to heed after the Roos fell to Adelaide by 35 points last Sunday.

"We probably just panicked a little bit at times, especially coming out of the back half. That's usually where we get our launch from and that's what we'll be looking to do this Saturday," Duffin said. 

Entry is free for both games, with plenty of family-friendly activities and entertainment at the ground to mark the release of Marvel Studios’ Captain Marvel movie, including an interactive mural, an obstacle course, a ‘Code Like a Girl’ mobile classroom, competitions and giveaways.