The poor finish notwithstanding, the 36-year-old has established himself as one of the best in the world over the past year.
The triumph also renewed talks of Tiger Woods making a run at Jack Nicklaus’ record of 18 majors.
The 3-times major champion launched his drive 332 yards up the fairway and then made an eagle after his approach shot settled 10 feet from the cup.
A victory would be Woods' fifth, leaving him second behind six-time champion Jack Nicklaus.
Forecasts predict severe thunderstorms for late afternoon in the vicinity of the famed course, when leaders would normally be battling for the Green Jacket.
The 4-time major winner fired a one-under par 71 to stand on level par 144 in a share of 36th after 36 holes at Augusta National.
The Englishman's performance was a surprise since he had arrived at the tournament in fine fettle.
After an ordinary outward nine featuring three birdies offset by a pair of bogeys, Woods embarked on one of his trademark charge.
Woosnam announced three years ago that he had played at the Masters for the last time, but subsequently changed his mind.
Several prominent players were still on the course when the horn blasted, including Rory McIlroy and Tiger Woods, who had just hit his tee shot on the par-three 12th.
Tiger Woods and Jack Nicklaus have won 32 majors between them, dominating their respective eras.
Brooks Koepka enjoyed a four-hole birdie run from the 12th to pull ahead.
After a routine par at the opening hole, former world number one Tiger Woods picked up a birdie at the par-five second.
Scott, who won the Masters in 2013, has achieved only one top-10 finish at Augusta since.
Tiger Woods teeded off in the 83rd Masters opening while James Harding secured the lead.
A blistering start in 2019 would not hinder Rory McIlroy to a Grand Slam career.
The contest sees Masters competitors and the old guard play on a truncated course with shorter holes.
Augusta National held its first women's tournament last week on the same course that will play host to the men's major.
The 61-year-old thinks that sooner or later a grey-haired older player will win a major, perhaps even the Masters.
The new formula for the 29-year-old centres around meditation, juggling and mind training.