McIlroy surges into contention ahead of final round at Quail Hollow
Schauffele, who held a four-stroke lead heading into Saturday's round, shot a one-under 70 to leave him 12-under through 54 holes.
A week that began with yet more talk of McIlroy's role in trying to bridge golf's divide with the Saudi-backed LIV Golf League, with confusion over a potential return to the PGA Tour's policy board, will end with the world number two battling for his second title of the season.
It would also be his fourth win at the Charlotte, North Carolina course, scene of his first victory on the PGA Tour back in 2010.
McIlroy's decision to compete two weeks ago at the Zurich Classic of New Orleans team event was seen by some as simply a gesture of commitment to the PGA Tour from a player who has positioned himself as one of its biggest defenders.
But McIlroy insisted that the tournament, which he won with Shane Lowry, would help him find form after his disappointing showing at the Masters and his performance in North Carolina has, so far, entirely justified that decision.
The Northern Irishman was the only player to go bogey-free in Saturday's third round and he was at his very best with driver in hand.
McIlroy is the best in the field in strokes gained off the tee and in driving distance this week and his opening birdie came on the par-4 fifth when he hammered his drive 341 yards down the fairway before landing his chip four feet from the hole.
He birdied again on the par-4, ninth, where his 180-yard iron shot left him a ten-foot putt and he was immaculate all-round on the par-5 10th.
Schauffele disappointment
His final birdie came on the par-4 14th and after his round McIlroy was quick to credit his experience in Louisiana last month for his outstanding driving rather than his sessions with veteran coach Butch Harmon.
"I would say that's a direct result of some of the feelings I got in New Orleans a couple of weeks ago. A lot of the stuff Butch and I worked on was more like iron play and wedges," he said.
"The driving is more just me committing to most of the time hitting that little cut that I've been hitting off the tee, and then having the freedom to just, every time I hit a good tee shot, the more confidence I get and then the more I want to just keep hitting it," he added.
American Schauffele made birdie on the par-5 seventh but bogeyed the par-4 12th where he missed an 11-foot putt for par but ended one under after a birdie on the 14th.
After his opening round of 64 and 67, Schauffele was disappointed with his Saturday play.
"Not as clean. Some sleepy wedges in there unfortunately, some really good up-and-downs, kind of a mixed bag. Definitely made it harder on myself is what it felt like from being in some good spots in the fairway," he said.
South Korea's Im Sung-jae is four shots off the lead after his 69 which ended with contrasting fortune on the final two holes.
Im struck the flag on the par-3 17th, with the ball rolling off the green but he scrambled to make par.
Then on the 18th, he chipped in from the sand to save par.
Austrian Sepp Straka is a further shot back, after a round of 67 which included three bogeys.