The four-time major winner from Northern Ireland fired a hole-in-one at the par-3 16th to inspire cheers from the spectators as loud as anything tournament play has inspired among the Georgia pines.
“I don’t think I’ve ever heard a roar that loud in a practice round,” McIlroy said.
The 26-year-old used a 7-iron to connect from 170 yards and ensure he owned bragging rights for the round over playing partner Chris Wood of England.
McIlroy is trying to win the Masters to become sixth player to complete a career Grand Slam, joining Jack Nicklaus, Tiger Woods, Gary Player, Ben Hogan and Gene Sarazen.
He has captured the 2011 US Open, the 2012 and 2014 PGA Championships and the 2014 British Open, but all of those came after he led the 2011 Masters only to squander his chances for a green jacket with a nightmare back nine on Sunday.
“What’s great about Augusta National (is) we have really good drama on the back nine on Sunday,” said reigning British Open champion and 2007 Masters winner Zach Johnson.
“It’s an aura about it. It’s really hard to pinpoint. It’s something intangible. Something that especially if there’s multiple names up towards the top, you just feel like there’s something that’s going to happen and it just does.
“When you have the best players in the world playing the back nine at Augusta on Sunday, the best comes out. I don’t know what it is about that side, but it just brings the best, and sometimes the worst, out in everybody.”
Relax on focus for a single shot and title hopes can vanish into the water or the pine trees, as McIlroy knows all too well.
“If you’re not mentally prepared for it, the pin placement is there, the wind is here, you have to land it there, yeah, it bites you,” Johnson said.
“Am I feeling comfortable? I’m still not comfortable. There are certain things that are just difficult.”
Dustin Johnson, whose sixth-place effort last year was his best showing in six Masters starts, agreed, saying, “There’s a lot of opportunities to make birdie and then there’s a lot of opportunities to make disasters, too.”
Sweden’s Henrik Stenson, also seeking his first major title, warns against rushing into any shot at Augusta National.
“You’ve got to be patient,” he said. “It’s just the margins for error are so small.”
A host of worldwide stars are expected to be among Sunday’s back-nine contenders, including recent US PGA winners Jason Day and Adam Scott of Australia, two-time Masters winner Bubba Watson of the United States and Charl Schwartzel of South Africa, who birdied the last four holes to win the 2011 Masters.
Defending champion Jordan Spieth got his first in-depth sense of the Augusta National atmosphere as a Masters winner.
“It’s a different feeling on the grounds having won the tournament,” Spieth said. “It was a dream come true for me, so when I’m here, all that comes back to me. It’s really special.”
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Owls make virtually zero noise while flying.