The Adelaide-based journeyman had a dream return to the country of his birth as he shot a flawless seven-under par 65 at Kingsbarns to blaze a trail in the St Andrews-based pro-am which, as well as top golf pros, attracts Hollywood A-listers, billionaire businessmen and sporting superstars.
After a season of struggle, and coming off the back of two missed cuts, the 24-year-old Links Championship debutant opened up with four birdies in his first six holes and recorded another three on his inward stretch to join another surprise outsider, Scotland's world No.979 Michael Stewart, as co-leader.
Stewart shot his 65 at the tougher Open course of Carnoustie, with the event's third venue being St Andrews' Old Course, the home of golf which Buchanan may already be dreaming of gracing in Sunday's final-day shootout.
His round quite eclipsed the likes of Cam Smith, who won the Open at St Andrews in 2022 but opened up with a level-par 72 at the same Kingsbarns course.
Smith's LIV Golf teammates also joined a 20-strong Australian invasion, the most ever to play at a single edition of the event, with Marc Leishman shooting a three-under 69 on the Old Course, Elvis Smylie a 70 at Carnoustie and Lucas Herbert 71 at Kingsbarns.
Buchanan, who was a fine amateur and has won twice on the Australasian tour, was left delighted by an upsurge in form as he and Stewart held a one-shot lead over South Africans Casey Jarvis and MJ Daffue.
"It's been a bit of a struggle this year. Kind of missed a few cuts by one but I definitely feel like I'm becoming a better player before it starts to click a little bit," said Buchanan, who'd missed back-to-back cuts at the European Open and BMW PGA Championship.
"Obviously this is probably one of the easier courses out of the three, but yeah, it's a good start. My approach play was really good, I basically hit 18 greens. Took a little bit of stress off myself and made a few birdies."
The big names are lurking, though. Matt Fitzpatrick, who arrived in Scotland off the back of his fourth win of the year at the French Open, shot 68 at Carnoustie, with Ryder Cup teammate Tommy Fleetwood two-under and five-time major winner Brooks Koepka three-under on the same course.
