The defending champion went into Saturday with a record six-shot lead but any thoughts of a cruise to a second Green Jacket were soon dismissed on a topsy-turvy afternoon.
While those chasing took advantage of perfect conditions on a low-scoring day, McIlroy struggled off the tee and found himself trailing as he exited Amen Corner.
A pair of birdies had him back in front but another wayward drive led to a fifth dropped shot of the day on the 17th and he will head back out on Sunday locked at -11 with American Young, who carded a brilliant 65.
Sam Burns was then at -10 after a 68, one clear of Shane Lowry who carded the same score 68 with a hole-in-one.
Jason Day and Justin Rose sat at -8, with Scottie Scheffler 65 and Haotong Li a shot further back -7
McIlroy completed the career Grand Slam with his victory here last season, going on to win his home open, the Race to Dubai and the Ryder Cup with Europe in what was a standout year.
He has not quite hit those heights consistently so far in 2026 but he was at his brilliant best on Thursday and Friday and knows what is required in round four.
"The course was obviously gettable," he said. "There was a lot of good scores out there and obviously the quality of the chasing pack is obvious. There was a lot of guys that shot good scores.
"There's a lot of guys in with a chance tomorrow. I'm still tied for the best score going into tomorrow, so I can't forget that, but I do know I'm going to have to be better if I want to have a chance to win.
"There's a long way to go. This golf course has a way of... when you're not quite feeling it, you struggle. You have to dig deep and I felt like I did that on the front nine and made a lot of good par saves."
Young was +4 after seven holes on Thursday but has registered just two bogeys since and is riding the crest of a wave as THE PLAYERS champion and standout US star of last year's Ryder Cup.
"It's something I've dreamed of doing for a long time," he said of potentially winning a Green Jacket. "I like the position I'm in. If you had said on Thursday at about noon that I was going to be within a couple of the lead going into Sunday, I would have taken it in a heartbeat, especially given the fact that I was watching Rory play.
"Anytime you're around the lead in a Major, especially here, anything can happen. We saw today a slow start and a hot start can erase a lot. It's just kind of a matter of keeping myself in it tomorrow and doing the best I can to stay around the lead for as long as possible, and you see what happens at the end."
McIlroy strode to the first tee exuding the sort of confidence his position merited but after a poor tee-shot and three putts from over the back of the first, his lead was trimmed to two.
Lowry was among those in a share of second thanks to a spectacular hole-in-one at the par-three sixth, only the seventh in history at that hole and Lowry’s second at the Masters after his ace at the 16th a decade ago.
McIlroy, meanwhile, was grinding, needing to get up and down to save par on the fourth, sixth and seventh while all those chasing were putting up red numbers
Li had made the most of the gettable second and third and birdied the fifth before he put a remarkable second to tap-in range at the eighth to get to -9.
He bogeyed the 13th after finding the water, however, and it was Young who emerged as the closest challenger.
THE PLAYERS champion had five birdies in his first ten holes and after seeing his tee-shot on the 13th find the fairway off a tree after a snappy hook, he took advantage with a two-putt birdie to get into double figures and two back as McIlroy made the turn in 36 after six straight pars.
A huge drive and towering iron on the 14th meant the 28-year-old was just one back before McIlroy hit a beautiful approach on the tenth and holed a six-footer to take a two-shot lead into Amen Corner, with those in third five back.
The duo’s dominance soon looked fragile, though, with McIlroy surrendering a double-bogey after finding the water at the 11th and Young dropping a shot after doing the same at the 15th.
Young bounced back with a 27-foot right-to-lefter at the 16th and he was the solo leader after McIlroy flew the 12th green and failed to get up and down for bogey.
McIlroy’s playing partner Burns made eight pars in a row after a birdie-birdie start but a brilliant approach at the treacherous 11th and putt from the fringe on the 13th had him alongside his partner at -10 as Young signed for his 65.
Rory had to scramble to save par on the same hole before he finally found a fairway on the 14th and used that platform to make a birdie, adding another with two putts on the par-five 15th to wrestle back the lead.
Another poor tee-shot then ultimately led to another bogey on the 17th with McIlroy missing a good birdie chance on the low side on the 18th for 73.
Rose – a three-time runner-up at Augusta National - was bogey-free in his 69 with birdies on the third, eighth and 13th, while Day made four birdies in a row from the 12th in a 68.
In his remaining holes, Li birdied the 14th but bogeyed the 15th and 18th 69 to sit alongside two-time champion Scheffler who carded a 65 for -7
Reed and fellow Americans Patrick Cantlay 66 and Russell Henley 66 rounded out the top ten at -6
EDIT>>> Canadians Nick Taylor T21 70 -3 and Corey Conners T44 71 +3.
Sunday will dawn another impossibly beautiful sunny hot, still Georgia day, the tapestry on which an epic chapter in the 90 year old Masters will unfold.
I will say traditionally it is not the norm to follow up a really low round with another as Rory displayed. I doubt therefore if Young 65 and Scheffler 65 will duplicate their scores, and Sam Burns couldn't play better.
The question of the day, can Rory follow Jack's 1975 epic Sunday win, with one of his own ?
europeantour.com
Bryan Angus (edit)
