Scott had strung together five consecutive birdies on the front nine and was at five-under when play was halted for 70 minutes due to the threat of lightning.
The Masters champion, whose first shot after the delay was a pulled tee shot at the 234-yard, par-three 11th, went on to card a five-under 65 that gave him a share of the lead with American Jim Furyk.
"I was hot when the rain came," Scott said. "Your first shot (back) is a little tough. I pulled it. And then just had to go and do the whole settling down thing again like teeing off at the first.
"I was going along nicely, I still felt. It's always tough with a rain delay like that when you're playing really well."
Scott did manage to pick up another shot with a birdie at the par-four 14th that gave him the outright lead and a chance at a 63, the record low round in a Major that has been reached by several players.
But the 33-year-old went on to bogey the par-four 16th after missing a five-foot par putt and rejoined Furyk in a tie atop the leaderboard.
Scott, who endured a rough end to last month's Open at Muirfield when he squandered his one-shot lead in the final round with a series of late bogeys, was back in top form as he set off on a birdie binge from the par-five fifth.
"Probably the best run I've ever had and I just hit really nice shots and didn't leave myself too much work," said Scott, who hit 12 of 18 greens in regulation. "You have to take advantage of that and I was through the turn there.
"It was a dream start after kind of a nervous first couple holes."
Scott has some way to go to bookend what has already been a stellar campaign with another Major victory but he is oozing confidence.
"The results are showing that I have got something figured out," said Scott, who made a long-awaited breakthrough in golf's elite championships with a playoff win at the Masters in April.
"I don't know if you ever have it all figured out. I like what I'm doing, so I am just going to keep doing it."