Completing the career Grand Slam last year - ending 11 years of heartbreak and hurt - was a huge relief for McIlroy.

As the champagne corks popped around him, the five-time major champion was already speaking about how he believed finally landing the Masters would "free" him up for further success.

Feeling liberated from the weight of history would, he hoped, provide autonomy between mind and body at the sport's biggest tournaments.

In practice, that did not immediately prove to be the case, leading to doubts about his form going into his Augusta return.

But by the midway point of his opening round, that freedom was visible in his swing and in his stride.

McIlroy did make a tentative start before finding his rhythm and clicking into gear with a flurry of five birdies between the eighth and 15th holes.

Ending with a 67 meant he carded his lowest opening round at Augusta since 2011. It was only the third time in his career he has shot under 70 on day one.

"I still have high expectations of myself, but my expectations are more did I make good decisions? Was I committed? Was I trusting? It wasn't my expectation that I'm going to go out and shoot 65," McIlroy said.

Some have wondered how McIlroy would deal with the additional responsibilities which occupy the reigning champion.

There is no doubt it is a completely different week for the previous year's winner, even more so for McIlroy given the magnitude of his achievement and the tumultuous journey to get there.

More engagements to attend. More interviews to conduct. More hands to shake.

Less time, some feared, to prepare.

A relaxed McIlroy had warned, though, he was ready to get down to business once Tuesday's Champions Dinner and Wednesday's Par 3 Contest were out of the way.

When he stepped inside the ropes on Thursday, McIlroy was finally able to lock in and stoke the competitive fire which has fuelled his outstanding career.

That's not to say this week's activities might still take a mental toll which ultimately affect his performance. It will be interesting to see if he fatigues as a pleasurable but long week heads towards its conclusion.

"It's a great start but there is a long way to go," said McIlroy, who started with a level-par 72 on his way to glory 12 months ago.

"It's a lot better than starting seven behind going into the second round like I did last year."

McIlroy's opening round was a study in experienced score-building. He didn't have his best stuff tee-to-green, hitting five out of 14 fairways and 12 of 18 greens in regulation.

But he managed to recover from errant tee shots and duly attacked when in position.

As ever around Augusta's immaculately manicured turf, the par-fives were critical. He birdied all four of them despite not hitting a fairway.

There was no panic. He looked every bit the seasoned champion who has seen it all in his 18 years coming here.

He was in the trees on the second, 13th and 15th holes but didn't ride his luck. Instead, he took his medicine, chipped back into position and it yielded three birdies. In the rough on eight, he drilled a low fairway metal that chased up the green for a two-putt birdie.

When McIlroy's driver behaves, he can make the game look easy. That was the case on nine and 14, where he set up birdies with huge carries off the tee and controlled approach play.

His only slip-up came on the short par-four third, where he badly overcooked his second and took three putts from 49 feet.

Despite the wayward drives, McIlroy steered clear of the mid-range par putts that can ramp up the pressure and derail momentum.

As he said himself, it's a "great start" and nothing more. But given he was seven shots behind Rose at this stage last year, he will feel content with his first round as defending champion.

If any storyline is going to come close to the romance of McIlroy's win last year, it would be 45-year-old Rose finally securing a Green Jacket and becoming the second oldest winner in Masters history.

Rose was a shot behind McIlroy and Burns before dropping back after successive bogeys on 17 and 18.

Nevertheless, the Englishman focused on the clear positives after finishing inside the top 10 after the opening day for the 10th time in his career.

"I look at the big picture. It was a good round of golf on a day which was challenging. Small margins but overall a good start to the tournament and I can build on it," Rose said.

Scheffler, 29, has fallen below his lofty heights in recent weeks, lacking some of his precision from tee-to-green and paying the price for slow opening rounds.

But the two-time champion made a blistering start with an eagle on the second and a birdie on the third.

While the world number one could not add to the tally, he largely demonstrated the consistency for which is he famed to eke out a solid, if unspectacular 70.

England's Tommy Fleetwood surged up the leaderboard with a run of three successive birdies from the second. A fourth followed at the ninth.

But four bogeys aside of a solitary birdie on the back nine sucked him back into the chasing pack as he opened with a 71.

Scotland's Robert MacIntyre plunged towards the bottom of the leaderboard with an eight-over par 80 – which featured a quadruple bogey nine.

The 29-year-old left-hander was picked out by some observers as a potential contender after finishing fourth at the recent Players Championship and a runners-up spot in Texas last week.

MacIntyre was already three over par in his round when his mood darkened further on the par-five 15th.

He emulated 1992 winner Fred Couples - who went from two under to six over in the space of three holes - by also hitting two balls in the water as they ended up posting nines.

Spain's Jon Rahm, who is known for his own tempestuousness and was heavily backed to perform well this week, also had a day to forget.

Rahm shot a six-over 78 - the worst Masters round of the 2023 winner's career - while his fellow LIV player Bryson DeChambeau carded a four-over 76. Much of that damage was done on the par-four 11th where posted a triple-bogey seven after taking three shots to emerge from a greenside bunker.