His throttle jammed wide open at McPhillamy Park, causing him to hit the concrete wall in a gap in the tyre barriers.
His injuries included two fractured ankles, a fractured sternum, fractured lumbar and thoracic vertebrae, cracked ribs and bruised lungs.
The recovery was long and painful and ended his participation in Supercars.
Radisich has kept his hand in driving the odd endurance race, historic event, BNT V8 Championship and Historic Touring Car Racing.
Radisich jumped at the opportunity to take part in the winner-take-all three-race decider.
"I'm a big fan of the TCR, and it's about getting in behind the class and to show everybody what the cars are about.
"If I can do my bit to get the series noticed and up and running, I'm happy to be involved. Covid has made things a bit difficult, so here's hoping one intensive weekend of TCR racing will get people excited and build the championship up."
While it's been a few years since he raced full-time, Radisich hasn't lost any of his competitive spirit and isn't looking at the weekend to cruise around mid-pack.
Not a believer in everything being 'in the good old days', he's keen on getting behind the wheel of a modern two-litre race car.
"I guess I made my name in this class. The two-litre class is the one that gave me a career.
"It's been decades since I drove a two-litre car in anger. I haven't driven the car yet [testing is later this month] but I'm thinking it'll be a lot nicer to drive.
"They have a lot more horsepower now and I'm hoping there's not as much understeer as the old two-litre cars. And of course they've got a bit more aero.
"I'd like to think they'll be a lot more refined and I'm fizzing to go racing again. I'm a competitive sort of guy, and as long as I can hustle along, I'm looking forward to the challenge and taking on the young guns," said Radisich.
TCR is an FIA-recognised global category, with numerous countries running national championships. There is a world series, with events primarily based in Europe. By getting a series up and running in New Zealand, young Kiwi drivers have yet another category option to race overseas and build a career as a professional motor racer.
There are 15 eligible cars, some of which are Alfa Romeo, Audi, Honda, Hyundai, Kia, MG, Peugeot, Renault, Volkswagen and SEAT.
"It's a great series for the young guys to learn race craft. If they think touring cars is the way to go for them, it's another path other than Supercars," said Radisich.
"TCR is a world category of racing and has manufacturers involved, which is a good sign.
"It's a cost-effective way of going racing and will give someone legs to make a career of their own.
"It's going really well in Australia, and TCR is scattered pretty much all through the world. There are lots of manufacturers involved and you buy into the TCR. The manufacturers supply most of the parts and you can get them from your local dealer.
"It just makes it easier to go racing, and manufacturers will be looking at who's driving the car and how good they might be."
Radisich will be driving a Volkswagen for the M-Development team.
