A double-bogey 6 at his opening hole, the tenth, followed by a quadruple-bogey 8 at 18th, where he pulled both a driver and iron into the water, contributed to McIlroy signing for a seven-over-par 79 at TPC Sawgrass in Florida.
It was the worst opening round score since Lyle carded the same number in 1988, with the 8 matching McIlroy’s worst hole in his PGA Tour career and an outward half of 43 also tying his worst effort for nine holes on the circuit.
The four-time major winner’s nightmare was in stark contrast to Garcia’s opening effort as the 2008 champion and two-time runner-up finished birdie-birdie-eagle to set the pace in the $15 million event with a seven-under 65.
The brilliant effort gave the Spaniard a two-shot lead over American left-hander Brian Harman, with Open champion Shane Lowry who was out in 32 before making a 2 at the iconic 17th, dropping a shot at the last after also getting to five-under.
It was a case for deja vu for McIlroy, who had also put two balls into the water when taking a double-bogey 7 at the sixth hole at Bay Hill in the final round of the Arnold Palmer Invitational last Sunday.
“I just hit a drive that started 10 yards left of where I was aiming and went on the wind and did the same thing with the 4-iron,” said the Northern Irishman of his latest disastrous hole, having taken the latter from a forward tee at the point where his tee shot had crossed the line of the hazard.
Earlier, he’d badly pulled a 3-wood with his opening tee shot, which led to a penalty drop, and later in the round he was fortunate not to get wet again with another wayward blow left with an iron.
“Very hard,” he replied to being asked how tough it had been to recover from his start, “especially when you're trying to figure it out as you go along on the course but you still know you're not really sure where the shots are coming from.
“Obviously the big number on 18 didn't help and then doubling the first wasn't helpful, either.
“But it's hard to recover when you just haven't played good. I mean, regardless, if you take that 18th hole out, it still wasn't a very good day.”
In contrast, Garcia was majestic at times, especially at the end as he followed back-to-back 15-foot birdie putts at the seventh and eighth by rolling in an 18-footer for an eagle-3 at the ninth.
Garcia also eagled the par-5 16th - his seventh - as the Spaniard shot his 25th round in the 60s in this event - the most of any player in its history.
“I just love it,” he said of the Pete Dye-designed course in Ponte Vedra Beach. “I've always said it, Valderrama and this course are some of my top favourite ones.
“It just kind of fits my eye. I see what I want to do pretty much every hole and then it's a matter of doing it.”
Offering his thoughts on McIlroy’s day, the leading Ryder Cup points-scorer of all time added: “I love Rory, he's an amazing player.
“But this course, you don't have to be that far off to get penalised a lot. So it happens. When it feels like you're not making any ground, you try to force things a little bit and, unfortunately for him, it bit him a little bit.
“But I told him when we finished, just go out there tomorrow and get it and you never know, I shot seven-under so he can shoot seven-under tomorrow and hopefully make the cut. So we'll see. He's able to do it.”
Englishman Matthew Fitzpatrick and Canadian Corey Conners shot matching 66s, with Bryson DeChambeau and Lee Westwood, who finished first and second respectively in the Arnold Palmer Invitational, both opening with 69s
“Obviously I built a lot of confidence last week,” said the 47-year-old Westwood after carding five birdies, “and this is a place where I've played a lot and I've played well before.
“I played solid. I hit 17 greens in regulation. Hit a lot of fairways, as well, and I putted nicely. Even if you're on some of these greens, it's not easy to still make par.
“So you had to be conservative in places, play smart golf, strategic golf, and that's what I tried to do and pick up the odd shot.”
Westwood’s effort came in the company of Bob MacIntyre, who recovered from being four-over after just five holes to card a two-over 74 on his debut.
Russell Knox fared best amongst a trio of Scots with a 71 that included four birdies, with Martin Laird having to settle for a 73, the same as world No 1 Dustin Johnson, despite being two-under after 12 holes.
Viktor Hovland signed for a 70 but that later became a 72 after the Norwegian was handed a retrospective two-stroke penalty for failing to replace his marker on the 15th hole.
On a day when a combination of wind and a firm green claimed lots of casualties, the most pain was suffered at the par-3 17th by former BMW PGA champion Ben An.
The Korean hit four shots in the water as he ran up an 11 - the second-highest score there in the event after Bob Tway’s 12 in 2005.
A double-bogey 6 to finish saw An sign for an 11-over 83, two less than 2016 Open champion Henrik Stenson after a horror show for the Swede made up of halves of 44-41.
The first round was suspended due to darkness at 6.32 pm local time, with 21 players left on the course and will resume at 7.30 am Friday. The second round will begin as scheduled at 6.45 am.