Justin Rose raced into a four-shot lead on Thursday thanks to a superb back nine that saw him finish on seven-under par.
Despite being two-over after seven holes, the Englishman rallied and hit an eagle on the eighth and seven birdies between the ninth and 17th to close four shots ahead of second-placed Brian Harman and Hideki Matsuyama.
The first round also saw a number of pre-tournament contenders struggle.
“I knew two-over through seven is not the end of the world, but also knew you’re going in the wrong direction,” Rose, twice a runner-up at the Masters, told reporters of his slow start.
“You can’t win the golf tournament today. Even with a 65, you can’t win it today. You can only probably lose it today.
“I didn’t hit the panic button yet (after seven), but I reset just prior to that and thought if I can get myself back around even par, that would be a good day’s work.”
It’s the fourth time that Rose has led or co-led the Masters after the first round, a record he now shares with Jack Nicklaus.
The 40-year-old, playing his first tournament since withdrawing from the Arnold Palmer Invitational last month with a back injury, was one of only three players to finish under 70 alongside Harman and Matsuyama — quite the contrast to last year’s tournament when 24 players shot sub-70 scores in favorable November conditions.
Rose’s only previous major triumph came at the 2013 US Open; the closest he has come to securing a Green Jacket at the Masters was in 2017 when he was beaten in a playoff by Sergio Garcia.
“I’ve played this course many, many times, it’s my 15th Masters, maybe, and my best to date is 67,” Rose said.
“I felt like the conditions today were not the day to go hit them and have your personal best out there.
“It was pretty windy — windy enough to be tricky — and obviously the greens are incredibly firm and fast. The pin placements were fair, certainly not easy, but fair, and if you did hit the right shot at the right time, you could take advantage.”
As for those further down the leaderboard, DeChambeau came into the Masters armed with a new driver and plenty expectations, but the big-hitter landed a number of tee shots off the fairway in the first round.
His 76 included a double bogey at the fourth and bogeys on the fifth, eighth and 12th before his sole birdie on the 15th.
DeChambeau was joined by McIlroy on four-over, the Northern Irishman having finished in the top 10 at August National on six previous occasions but never securing a Green Jacket.
Well-positioned on one-under with three holes to play, Johnson bogeyed the 16th and double bogeyed the 18th after his putt lipped out of the hole.
2018 champion Patrick Reed ended the day tied for fourth on two-under, while Justin Thomas and Jon Rahm — second and third in the world rankings — finished on one-over and par respectively.
CNN’s Ben Morse contributed to reporting.