McRae worked as Richmond assistant and VFL coach under Hardwick from 2016 to 2021, including winning the 2019 VFL premiership, then had a stint at Hawthorn before landing the Collingwood head coach role.
But don't expect any banter or cheeky texts in the build-up to Saturday's match at the MCG.
"We've always been very, very funny like that. The week leading in and the week after we probably steer away," Hardwick said.
"But they're going really, really well. I think Fly (McRae) is a terrific young coach, and he's got Leppa (Justin Leppitsch) there as his assistant as well.
"So they've certainly got a good understanding of what we do and how we operate but in fairness so have we on the way they're going about it.
"With both sides playing a similar style of game, we look at our our metrics and KPIs and they're very similar the way Collingwood are playing.
"He's got a good blend of experience and youth, exciting youth as well.
"He's got them playing what we feel is a great brand of footy and a sustainable brand of footy so they're only going to learn and get better."
McRae reminisced fondly on his time at Richmond but stressed the Magpies needed to be ready for the Tigers to be fired up off the back of regaining superstar Dustin Martin and former skipper Trent Cotchin.
"I can't speak highly enough of my time there. I'm just so grateful for the opportunity," he said.
"The five years were really special and I've got some great memories from that and clearly I'm not here without that opportunity.
"They played extremely well against West Coast. They're full strength.
"If you look at their line-up, There's a lot of premiership players back in this week and I know them well enough to know they're gonna bring their best.
"We've just got to make sure we're ready for what comes."
Collingwood will hope Nick Daicos, Taylor Adams and Brayden Maynard all prove their fitness after missing Thursday's training with the flu.
The Magpies have recalled youngsters Ollie Henry and Trent Bianco.
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