A second consecutive bogey had just seen the four-time Major winner slip to two over par, placing immediate doubt on his credentials this year of finally securing that elusive green jacket and completing golf’s grand slam.
Yet those suspicions will have been exacerbated on the very next hole.
The Northern Irishman found further trouble after finding the trees down the left with his drive from the seventh tee.
But it was his next shot which will have caused greater alarm – a lay-up which proved just as wayward as it amazingly struck his dad Gerry on the leg on the opposite side of the fairway.
In such instances, it’s customary for the offender to quickly apologise to the unfortunate victim and offer a signed glove or something to help ease the pain.
Yet when you’re the father of one of the game’s most recognisable players and a current A-lister, a frozen bags of peas seems the most likely peace offering.
‘He's seen me sign plenty of stuff over the years, so I think that's the least of his worries,’ quipped McIlroy.
‘I think he just needs to go and put some ice on it, maybe I'll autograph a bag of frozen peas for him.
‘It was a perfect shot; it was dead straight. But I think he was okay.
‘He didn't limp away. He walked away pretty swiftly, so that was all right.’
The world-number 12 would eventually go on to pen another bogey on his card – the third in a row, with six in total coming by the time he finished his round.
Two birdies helped contain the damage slightly.
Yet an opening-day score of 76 left the Ulsterman, who went into the first Major of the season battling unwanted forces in his swing, four over par and licking the wounds to his worst-ever start at the Masters.
Despite his difficulties and further evidence that his swing requires further analysis in the company of new coach Pete Cowan, McIlroy was insisting all was not lost.
Even if Ryder Cup team-mate and runaway leader Justin Rose already looks well out of reach on seven under.
Indeed, he was not the only one to suffer as Augusta National bit back after providing more user-friendly conditions at its last staging back in November because of coronavirus.
Most recent winner Dustin Johnston (+2), Bryson DeChambeau (+4), Justin Thomas (+1), Sergio Garcia (+4) and Lee Westwood (+6) were just some of the others who will want to quickly move on from day one which had only 12 players record scores under par.
‘Honestly, I'm quite encouraged with how I hit it on the way in.
‘I hit some loose shots out there, but after hitting the six-iron in the water on 13, I hit some really good shots coming in, so I'm encouraged by that.
‘I hung in there, hit some good shots coming in. Could have made a couple more birdies.
‘I was starting to get into a rhythm. I wish I could have kept going.
‘I might have given myself a few more chances. But there were some good shots coming down the stretch there.’