After a nervous opening swing, Scott found trees well right, forcing the 33-year-old to make a great up and down for par. The Queenslander began striking the ball as flush as could be and looked set to give the so far unattainable 62 in majors a real shake.
At the very least the course record of 64 looked vulnerable.
He created a beautiful run of five birdies from the fourth to the eighth holes to rocket into the share of the lead and made the turn in 30.
"It was probably the best run I've ever had," Scott said of the blitz.
"I just hit really nice shots and didn't leave myself too much work. It was a dream start after kind of a nervous first couple of holes."
But after a par on the 10th, Scott headed to the par-3 11th only for play to be suspended for a thunderstorm.
After an hour's delay, Scott's heat had dissipated and while he moved it to six-under with a birdie at the 14th, he three-putted the 16th to put paid to any record run.
A great final-hole par save ensured he would take a piece of the lead.
"I was hot when the rain came and to go back out and have 234-yard par three with your first shot is a little tough. I pulled it," Scott said.
"I was starting to feel it slip coming in on the last three holes so to make one on 18 and get something out of the round that I felt could have been special was a nice feeling."
Scott admitted it felt a little like his previous best round in a major, a 64 from round one of the 2012 British Open.
"It was very close. I felt good out there today," he said. "I felt like I could swing freely and I was hitting all the shots that I wanted to hit.
"When you get something going for you in a major, sometimes you have got to be not afraid to get out of your own way and let go, and I did that at Lytham and I did that here for 10 or 11 holes."
Scott is looking to be the first Australian to win two majors in the same year and the first player to bookend the season's first and last majors since Jack Nicklaus in 1975.
"If I can go out with some kind of momentum tomorrow morning off today's round, I know there is a good score out there," he said.
World No1 Tiger Woods struggled to a 71 to be six shots off the pace in his quest for a 15th major championship.
Marc Leishman got through his opening round without wife Audrey going into early labour, shooting an even par 70 to be tied 36th along with Brett Rumford.
Matt Jones gave away three shots in his final two holes to back up to 72 where John Senden also sits in 74th.
Geoff Ogilvy rounded out the Australian tilt with a 74 to be tied for 108th.
- AAP
