Speaking on the KTM Summer Grill, Percat revealed that he underwent surgery just days before track action kick off at Mount Panorama.
The issue was a run-in with a grinder while working on a go kart in Malaysia on the Sunday before the Great Race, which left a finger on his left hand badly damaged.
That forced him under the knife back in Melbourne on the Monday before Bathurst, Percat keeping the injury under wraps, even from his own team, until the end of the weekend.
“I was in Sepang with Brad Majman, one of my junior drivers,” said Percat, who is heavily involved in karting outside of his Supercars commitments.
“We went over there for quite a big race and it was all going swimmingly. I thought I’d do the right thing and put a fresh axle in [his kart] for Sunday, because it had done a fair bit of work.
“We cut the axles down to change the grip level, and I managed to basically cut my finger off in the process.
“I flew back with it all bandaged up after about an hour in the medical centre [at Sepang]. They were pulling parts of the grinder off my bone.
“By chance, the doctor there was a surgeon and had a serious chat with me. He said, ‘if you don’t get this fixed tomorrow in Melbourne, you’re in a drama for infection’.
“Luckily [Supercars medical delegate] Dr Carl [Le] was amazing and put me in touch with the right people. I landed at midday, straight to hospital, surgery at three o’clock.
“I walked out of there with nothing on it. [The surgeon] said, ‘just start moving your finger. I’ve sewn all the tendons back together and sculpted the bone back – you’ll be good to go’.
“So, I kind of drove Bathurst with a bit of a pistol look, which the karting kids found hugely hilarious when they tuned in to my on-board.
“It wasn’t ideal prep, but I managed to keep it on the down-low from the team. They didn’t really realise until Sunday when I took my glove off and there was stitches and blood everywhere.
“It’s all good now, though. [My fiancee] Bailee has banned me from using the grinder the week before a Supercars event.”
For more from Nick Percat check out the full episode of the KTM Summer Grill.
As part of this year’s KTM Summer Grill, each day for three weeks KTM is giving away a bar stool, mug and pit board-style wall clock. Click here to win.