The Black Ferns may be in World Cup mode, but they were in full attendance at Spark Arena last night to cheer on other ferns doing their best for New Zealand on the sporting stage.

After opening their campaign at Eden Park with a 41-17 win over the Wallaroos, the Black Ferns got to enjoy watching the Silver Ferns have the same success over the Diamonds – although the trans-Tasman battles weren’t the only matching details.

While Sulu Fitzpatrick didn't get on the court last night, it’s still been a special and unique week for her and rugby-playing sister Theresa; the two staying in the same hotel this week on Constellation Cup and Rugby World Cup duties.

"The rugby girls, they're loud, different cultures, but I think it balances it out, so it's been really nice to see them at all the meals," Sulu said.

They brought that noise last night, with Theresa saying Stacey Fluhler led the cheer leading charge.

"I was just following Stacey's lead, she's the ring leader," Theresa said.

"She probably doesn't even need me to try and make her louder, because I'd still get drowned out by her."

The sisterly support comes after Sulu was adopted into the Fitzpatrick family as a young child, growing up with Theresa to have successful sporting careers, albeit along slightly different paths.

"We started off playing league and Sulu didn't actually like the getting dirty and all the mud and what not," Theresa laughed.

"We transitioned into netball - my sister would just be on one end of the court and yell my name and I'd just have to get free and make sure I could catch the ball from wherever I was on the court."

They'll play respective Tests on Sunday - the rugby in Auckland in the afternoon before the netball tips off in Tauranga later in the evening.

It means mum faces a bit of a peculiar challenge.

"Her plan is to do both within an evening, but I've told her it's not worth it," Sulu said.

"She said she can get to my game by halftime but I said do not do it. Knowing her, she'll probably end up coming."

After all, it's not every day the Fitzpatricks fly the fern just a few hundred kilometres apart.