Tied with Englishman Richard Bland on 7-under, the pair leads the second over-50 major championship of the year by two shots from a five-strong group that includes Mike Weir (Canada), Steve Stricker (US) and K.J. Choi (Korea).

“It was an exceptionally good day. You know, it’s a very challenging golf course, and one that can really bite you at times,” Green said.

“The start of the day it was to go out there and treat it with as much respect as possible and play good golf shots, and I was doing that, which was nice. Got off to a great start.”

One of 14 Aussies in the field in Michigan, Green’s “great start” came in the second group of the day with immediate success following a birdie at the par-4 first with another at the third before switching to another gear two holes later.

Taking on the par-5 fifth in two, the Victorian nearly didn’t need his putter as the ball took a look going past the hole before the left-hander rolled in his eagle putt to reach 4-under.

“Hit a great drive down five and left myself about 250 yards to the flag I think I had, something like that. I knew my hybrid carries around the high 220s,” he said.

“Hit it just perfect and just shaped it in there nicely and it was tracking towards the hole. I think it ran across the edge of the hole and finished about maybe seven feet past the hole; then hit a really nice putt and made it.

“So that was obviously one of those exceptional holes at the right time and get the round going really well.”

Green would drop a shot at the next, before finding more joy on the par-5s when birdieing the ninth and 10^th holes, as well as the par-3 11^th to sit alone on top of the leaderboard on the Jack Nicklaus-designed course that is hosting the tournament for a sixth, and final time, this week.

His opening 64, which follows four top-15 finishes in PGA Champions events already this year, was only matched by Bland in the fifth last group of Thursday.

Vijay Singh is the next best of the Australasian contingent in a share of eighth on 4-under, while Scott Hend and Mark Hensby are another shot back in a tie for 13^th.

Making his first start on the PGA TOUR Champions after topping the qualifying school but needing to wait for his 50^th birthday earlier this month, Cameron Percy is in joint 20^th on 2-under alongside compatriots Greg Chalmers and Michael Wright.

The KitchenAid Senior PGA Championship is live on Fox Sports, available on Foxtel and Kayo.

Australasian Scores

T1 Richard Green -7
T8 Vijay Singh -4
T13 Scott Hend -3
T13 Mark Hensby -3
T19 Cameron Percy -2
T19 Greg Chalmers -2
T19 Michael Wright -2
T38 Stuart Appleby -1
T38 Rod Pampling
T65 David McKenzie +1
T65 Michael Long +1
T65 Mick Smith +1
T65 Brad Burns +1
T85 Steve Allan +2
T107 John Senden +4
T122 David Bransdon +5
WD Michael Campbell