Scheffler was five strokes clear with three holes to play and poised to become the first player to win four times in a five-tournament stretch since Tiger Woods in 2007/08.
A delay of two hours and 32 minutes on the course at Harbour Town in Hilton Head, South Carolina, due to storms and heavy rain meant play couldn't be completed and the round will resume on Monday. Scheffler, the world number one, sat on 20 under par for the tournament, with a quartet of players on 15-under.
He would also become the first player since Bernhard Langer in 1985 to win the Masters and then triumph at the Heritage, which is held the following week.
Scheffler's ability to get out of trouble, on the rare occasions he finds himself in it, was illustrated on the par-5 15th hole as darkness set in.
The American hit his approach shot way left into the water and was forced to take a penalty stroke, but he then hit his next shot to 12 feet from the pin and made his par putt, to ensure that he remains without a bogey since his double on the third hole in the first round.
"I felt like the par was pretty important tonight, just being able to go to sleep and still keeping a clean card. I felt like I got a bad break there in the fairway," he said.
"I haven't had to hit a shot like that in a long time, so I figured there must have been mud on the bottom of the ball. Just nice to keep the card clean," he said.
Scheffler began the day with a one-stroke lead but quickly extended that with an eagle on the par-5 second where he brilliantly chipped his third shot from 53 yards.
He made birdie on the next par-5, the fifth, after driving his second shot to 30 feet and two putting.
He ended up four-under for the day after birdying the par-4 13th, landing his approach shot six feet from the hole and making no mistake on the green.
Scheffler said he would treat Monday's final three holes as if it were another full round of golf.
"I will just go home as quick as I can, get some rest. I'll treat tomorrow like I'm playing 18 holes and do all my normal prep work and come out here ready to go for the restart," he said.
Clark charges
Wyndham Clark was the only one of the players tied for second to have finished his round - posting a six-under 65.
Clark threatened to go much lower than that after reaching the turn in 29 - with five birdies and an eagle on the second.
He stood at eight-under for his round after a birdie on the 11th but then undid half of his work with a double bogey on the 12th and bogeys on the 13th and 15th.
But he finished with birdies on 16 and 17 and was pleased with his work.
"Honestly it was a great day. I was trying to get myself in the top 10 and have a good finish, and it was kind of fun for a little bit. Seemed like maybe we had a chance to do something crazy." he said.
Also on 15-under is Patrick Cantlay, who has just a putt remaining on the 18th, J.T. Poston, also on the final hole and Sahith Theegala who is on the 16th.
Sweden's Ludvig Aberg, the runner-up at Augusta National last week, was a further shot back with one hole to play.
