Im regained his touch at Augusta National, firing an eagle and five birdies in a five-under par 67 that gave him a one-stroke lead over Australian Cameron Smith.
The 24-year-old powered up the leaderboard with birdies at the first three holes, and landed his 219-yard second shot 12 feet from the pin for an eagle at the par-five 13th.
“I birdied the first three holes and that got me into a good rhythm,” Im said.
“The 13th, I hit a good tee shot. The second shot, I hit a hybrid and it had a little bit of a draw, but it landed softly and I was able to convert that for an eagle. Overall, four good holes.”
Im said he was excited by the hot start.
“But I’m going to be humble,” he said. “I realize I still have three days to go.”
Im is well aware that fortunes can change on the iconic Augusta National course.
He enjoyed a memorable debut when the Masters was played in Nov 2020 because of the COVID-19 pandemic, finishing tied for second with Smith behind runaway winner Dustin Johnson - who on Thursday was in a four-way tie for third, two shots off the lead.
But Im missed the Masters cut last year, when his Presidents Cup Internationals teammate Hideki Matsuyma became the first Japanese Masters champion.
And since opening the 2021-22 US PGA Tour season with a victory in Las Vegas last October, he has been unable to find the winner’s circle again.
A share of 20th at the Arnold Palmer Invitational is his best finish over the past two months.
“I felt like my driving game was not as up to what it used to be, so I worked on my driving, and today the key to a successful round was having good tee shots, so that worked well today,” he said.
But the final boost came in Wednesday’s Par 3 Contest, the light-hearted family affair held on the eve of the Masters.
“I received some good vibes from my dad,” said Im, who played with his father, Im Ji-taek. “He hit a great shot at number nine.
“When he was setting up, we were at the tee box, Scottie Scheffler, Sam Burns and Billy Horschel, they were just having fun and having a crack at my dad, and it got me, too, so I was laughing.
“But once he hit the shot, it was the most beautiful shot I’ve seen. It was like a professional shot. It was definitely a fun day and a memorable one.”
Tiger Woods called on all of his hard-won stamina and the knowledge gleaned in five past triumphs to launch his boldest Masters bid yet with a one-under-par 71.
The 46-year-old superstar, whose Feb 2021 car crash left him with injuries so severe he feared he might lose his right leg, said just being able to play his first competitive round in 17 months was a victory.
But it might not be the only one he celebrates this week.
"I was able to finish up in the red," Woods said. "I’m right where I need to be."
Woods was tied for 10th, four shots behind Im.
McIlroy six off the pace
Elsewhere, Rory McIlroy stumbled six strokes adrift in yesterday’s opening round, his bid to complete a career Grand Slam in trouble after shooting a one-over par 73.
The four-time major winner from Northern Ireland shared 31st after 18 holes at Augusta National, bogeys at the par-4 14th and par-3 16th spoiling a solid start to leave him well back of Im.
“I don’t really care where I’m at on the leaderboard, or it doesn’t matter,” McIlroy said. “I played well. I hit the ball great from tee to green for the most part. So I’m pleased with that.”
The 32-year-old European standout, chasing his first major title since 2014, also salvaged a tough par at the 18th to provide some spark ahead of a morning charge today.
“It was good. I played really well,” McIlroy said. “I hit 12 fairways and 14 greens and just didn’t really get a lot out of the round.
“I had a putt on 14 to go to 2-under for the day with the par-5 to play, and I three-putt that, and that sort of halted any momentum I had.”
McIlroy finished his day at Augusta on the practice putting green trying to find form he hopes will make the scoring difference.
“I feel like it was the worst I could have shot today. I feel like I played really, really well,” he said.
“I’m encouraged with how I played so I’ve just got to try to get more out of the round tomorrow.”
McIlroy needs only a green jacket to become the sixth player to have won every major title at least once, a club that includes Tiger Woods, Jack Nicklaus, Gary Player, Ben Hogan and Gene Sarazen.
This week marks McIlroy’s 14th career Masters start and eighth attempt at completing the career Slam at Augusta National.
McIlroy dropped his third shot inches from the cup to set up a tap-in birdie at the par-5 second hole, but chipped eight feet past the cup at the par-3 sixth and made bogey.
He holed a 30-foot birdie putt at the par-4 11th, but missed a six-foot par putt at 14 and blasted out of a bunker at 16 and failed to convert a seven-foot par putt.
Things looked dire again at 18 when McIlroy found a greenside bunker, but he blasted out to six feet and sank the putt to salvage par.
McIlroy said his decision to play “negative” golf, not chasing so many pins in favor of safer shotmaking on several holes, paid off for him.
“I hit it to a lot of the middle of the greens and made a lot of easy pars,” McIlroy said. “I wish I could have gotten more out of the round, but it was pretty stress free.”