Seeking to win back-to-back events, Young threatened the course record at Quail Hollow on Saturday (Sunday AEST) before settling for an 8-under 63, leaving him two shots behind Alex Fitzpatrick at the Truist Championship.
Fitzpatrick was at 14-under 199 through 54 holes, one shot ahead of Norway's Kristoffer Reitan after each shot 64.
Adam Scott is the best-placed Australian, in a tie for 29th, after carding a third-round 66.
Min Woo Lee is two shots further back at even par for the tournament, following his third-round 72.
Young, who won last week's Cadillac Championship at Doral by six strokes, needed to play the final two holes in 2 under to break Rory McIlroy's course record of 10-under 61, set in 2015.
But his birdie putt on No.17 stopped inches from the hole and his drive on the 18th settled in pine straw behind a tree, forcing him to punch out and leading to his only bogey of the day.
"I know (the record was) 10 under and I knew I was at nine," Young said.
"But that wasn't my thought. I was just trying to hit it somewhere right of the hole on 17 and hit a couple good shots on 18. Unfortunately had one of my few bad swings of the day on 18."
Before that, Young had sent his shot from a fairway bunker 238 yards away to within a few feet of the hole on No. 7 for eagle. He seized that momentum to birdie six of his next nine holes.
Matt Fitzpatrick was one of the favourites to win the Truist Championship but it turns out little brother Alex is the one to watch this week.
Alex Fitzpatrick, who only earned his PGA Tour card two weeks ago when he teamed with his brother to win the win the Zurich Classic, rebounded from his only bogey of the day with a tee shot to 8 feet on the par-3 17th hole for birdie to reach 17 under.
Matt Fitzpatrick is a former US Open champion who's currently ranked fourth in the world, and Alex said having his brother to lean on has been invaluable.
"I feel like he's been and done everything that I want to do in the game — whether that's Ryder Cup and win majors," said Alex Fitzpatrick, who tied for ninth last week at Doral.
"So having him being around and me being there for all of that, I felt like I got a really good sense of what it takes and what the atmosphere is like."
Reitan, also a rookie, made some noise at the Masters before going 73-77 over the weekend to finish tied for 41st. He closed Saturday in Charlotte with four birdies over the final six holes to surge into second place.
Rory McIlroy, the world's No. 2 player and four-time tournament champion, had a disastrous day, shooting 75 to fall out of contention.
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