Rory is desperate to secure a passport to the World Cup at the end of the current campaign and the Scotland A clash with the touring Aussies sets up a potential return to national coach Frank Hadden's Six Nations squad.
Perth-born Rory, who made his debut on the wing opposite established older brother Sean against Wales in 2005, was taken along to Saints games by Woodside grandparents Allan and Jean Coogan when he was a youngster growing up in Blairgowrie.
And tonight, they will be among the McDiarmid Park crowd cheering on Rory and the A team which reached the final of the Barclays Churchill Cup earlier this year in North America, with their scalps including England.
Rory, who is fitter than ever after a double hernia was diagnosed belatedly and addressed by surgery over the summer, said in the Perthshire Advertiser: "It will be the first time I've played at McDiarmid but Sean and other lads have really enjoyed games there. Scotland set a new try-scoring record when they beat Japan 100-8. Sean was a bit disappointed just to get the one that night!
"My grandparents took me to football matches and I'm still a Saints fan, despite moving to England as a kid. I know the family are looking forward to the Perth game."
Rory is hoping to catch the eye in the clash with the touring Wallabies and he's been asked to step in off the wing to play in an unfamiliar inside centre role.
"I haven't played at number 12 since I was at U14 level, but Frank wants me to be more versatile. He believes I have the attributes required. I should see more of the ball in this role and carry it forward in the first phase. Last season with Glasgow we were losing games and I didn't see much of the ball out on the wing.
I'd love to get back into the international squad, especially in World Cup year. That is definitely my target.
"When I made my debut it all happened very quickly. I'd only played a handful of pro games when previous coach Matt Williams selected me. It was difficult to grasp at the time. Now I have a real hunger to succeed and get back to that level.
"To be honest, while I never rested on my laurels, I was quite nervous before – almost too nervous to enjoy the whole experience. I'm a more confident player now. I'd relish being in the mix for the Six Nations and World Cup."