"It was definitely a round of two halves," said Rose, who started on the tenth and bogeyed his first two holes. "I was just hanging on for dear life and then the rain stopped, put on a fresh glove and you began to feel like you could get after the golf course.
"Obviously I got hot and kept rolling with it. Adam played some great golf the last couple of days and showed me that this course is playable and you can make some birdies out there. And when I got hot, I stayed with it, which was nice."
Scott was initially caught by another Englishman, Lee Westwood, when play got underway in persistent rain but regained top spot when his birdie putt from 15 feet on the 13th just had enough pace to trickle into the hole, and he was soon two clear as Westwood dropped his first shot of the week on the 17th.
Seeking to become the first man since Jack Nicklaus in 1975 to win the Masters Tournament and US PGA in the same year, Scott then moved three ahead with a birdie on the 16th, only to follow Westwood in dropping a shot on the 17th.
Westwood admitted to being disappointed with a bad finish to his round, having seemingly done the hard work by getting through 16 holes in level par for the day.
But the 40 year old then ran up a double-bogey on the eighth and dropped another shot on the ninth to card a 73 that left him one under par at the halfway stage.
"I played pretty well," said Westwood, who is still seeking his first Major title at the 63rd attempt.
“The course was playing really long, the par four 17th was unreachable, and I was just ticking along before getting kicked where it hurts on the last two holes.
"I would like to have finished par, par but I am in red figures going into the weekend and still have a chance."
Ryder Cup hero Martin Kaymer secured a second consecutive 68 as the 2010 winner left himself well placed on four under par.