America’s Cameron Young held the clubhouse lead thanks to firing eight birdies in a flawless 64, a score only McIlroy himself has beaten in the opening round of an Open Championship on the Old Course.
McIlroy’s 63 came back in 2010 and was followed by an 80 in terrible weather, while an ankle injury suffered playing football prevented him from bidding to retain the Claret Jug at the same venue in 2015.
The four-time major winner admitted this week therefore felt like the title defence he never had and he enjoyed an ideal start, holing from 55 feet for birdie on the first and making seven in total in his 66, the same score he shot to begin his wire-to-wire victory at Hoylake.
In stark contrast, 15-time major winner Tiger Woods struggled to a 78 which began with a double bogey on the first after hitting his approach – from a fairway divot – into the Swilcan Burn, and took six hours and eight minutes to complete.
An opening 73 in April’s Masters meant McIlroy had been a combined 35 over par in the first round of majors since last winning one in the 2014 US PGA, but since then he has started with a 65 in the US PGA, a 67 in the US Open and Thursday’s 66.
“Yeah, fantastic start,” McIlroy said. “Just what you hope will happen when you’re starting off your week. I did everything that you’re supposed to do around St Andrews.
“I birdied the holes I should have and I made pars at the holes where you’re looking to make a par and move to the next tee, so overall really pleased.
“It’s another good start at a major, three in a row for me now, and I’m looking forward to the next few days.”
McIlroy is well aware that he has failed to turn those good starts into overdue wins, a third round of 74 doing the damage in the US PGA and a 73 at the same stage of the US Open proving equally costly.
“I need to go out tomorrow and back up what I just did today. I think that’s important to do,” he said.
“I’ve been playing well, I’ve been swinging the club well, and I think it’s better if I don’t think about it that much and I just go out and play golf and try to shoot some good scores on one of my favourite golf courses in the world.”
The parched conditions at St Andrews meant McIlroy was able to reduce the 614-yard 14th hole to a drive – which went around 400 yards – and a wedge, and he added: “It’s the fiddliest Open that I’ve played.
“Carnoustie was firm in 2018 but it wasn’t like this. I think as the tournament progresses, you’re going to get some funny bounces and it’s going to test your patience at times.
“Fiddly hasn’t really been my forte over the years, but I’m hopefully going to make it my forte this week.”
Young had missed the cut in his last two starts, but the world number 32 has recorded four top-three finishes on the PGA Tour this season and missed out on a play-off for the US PGA Championship by a single shot.
And the 25-year-old revealed this was not his first experience of playing the Old Course thanks to a family trip 12 years ago.
“I think my dad asked for permission to play from the back tees so when we came out to hit our first tee shots with the R&A building right there, there were a bunch of R&A members presumably watching,” Young said.
“And I’m glad I didn’t know, I’m sure I would have been nervous out of my mind. But I think there’s a picture of me hitting there with a bunch of those guys watching. That’s really my first memory of here.”
On a day when the early starters took full advantage of benign conditions, Australia’s Cameron Smith carded a 67 that was eventually matched at 10.10pm by English qualifier Robert Dinwiddie.
Amateur Barclay Brown returned a superb 68 which was equalled by the likes of Viktor Hovland, Dustin Johnson, Masters champion Scottie Scheffler and Lee Westwood.
Westwood’s fellow LIV Golf rebel Ian Poulter had been booed by a handful of spectators on the first tee due to his involvement in the Saudi-backed breakaway, but turned the jeers to cheers after holing from 150 feet for an eagle on the ninth in his 69.
There was disappointment for his Ryder Cup team-mate Justin Rose as he was forced to pull out with a back injury just before his scheduled 8.14am tee time, with Japan’s Rikuya Hoshino taking his place.
Sweden’s Alex Noren had been first reserve but he chose to travel to the Barracuda Championship in California.