The Blues will be without experienced forward Eloise Blackwell, who got a red card in the Super Rugby Aupiki final at the weekend, and No8 Liana Mikaele-Tu'u, who has a foot injury.
The game will be broadcast live on Sky Sport in New Zealand and Stan in Australia, and streamed for free on NZR+ in other markets around the world.
McGee thrived under the pressure of the Blues' 26-19 win over Matatū in the Aupiki final, scoring a 60m intercept try and pulling off a try-saving tackle.
When she scored her try, she told herself, 'Just run, don't stop.'
"And then when a Matatū player got their hands on me, I looked to see if there was someone else there, but there wasn't so I just had to keep running."
After finishing her schooling last year, Sorensen-McGee faced some tough career decisions before settling on playing for the Blues.
She played Touch Rugby for Counties Manukau in Under-16s and Under-18s and was looking to play rugby league, a game that runs through her family.
"I had an offer from the Warriors, but they were only offering me a development contract. I wasn't keen on that because I would miss some rugby things.
"Then I got a call from the Blues and then the Sevens. So I took that instead of the league path."
That has allowed her to share time with the experienced players in the Blues side, with wing Portia Woodman-Wickliffe having a big part in her development.
"It's been good for my personal growth. She's taught me a lot, and it's good being in this environment because I play with some of the best athletes in the world. It's good to learn from them, play off them, and then have them play off me as well.
"I still have a lot to learn, more in my kicking game. I do have a kicking game but it could improve a lot. And my defence can always improve and also my attacking skills."
From the outset, she was encouraged to back herself, which inspired her to play freely and confidently and to be herself on the field.
While concentrating on fullback she has a background of playing first five-eighths at school, but sees her future at fullback.
She knows what to expect from the Australians as a result of their pre-season game.
"They're really good with the ball in hand, but considering that was our first hit out, we did good against them and we can do it again. Their wings are fast, they've got a good kicking game we've got to be aware of that."
New South Wales will play without wing Maya Stewart, who suffered a concussion in their 43-21 Super Rugby W win over the Reds over the weekend.
Coach Mike Ruthven promoted Jade Sheridan as her replacement, the only change to the side that won the final.
He told rugby.com.au, "It's disappointing for Maya. She's had a fantastic year, and it's really disappointing she won't get the chance to travel with the team.
"But we're confident in the depth of our squad. It's an opportunity for someone else to come in, compete hard and go well."
Ruthven said his side was ready for the challenge of playing the Blues. They have been watching what has happened in the Aupiki competition and played the Blues in a pre-season warm-up game, which ended in a 36-all draw.
"They're a physical team, particularly competitive around the contact and collision areas.
"We'll be up for a big challenge. It's an important fixture in terms of the growth and potential expansion of the competition.
"We don't go over there feeling any burden, it's just another challenge."
Where to watch:
Thursday 17 April, 7:05pm NZT | 5:05pm AEST: Blues v NSW Waratahs – North Harbour Stadium, Auckland (Buy Tickets)
New Zealand: Sky Sport 1
Australia: Stan Sport
All other markets including US, UK and Ireland, Canada: NZR+ (sign-up free here).