Scheffler is trying to break a streak of five runner-up finishes and five other top fours since his lone victory to start 2026.
He is 13 under and will be in the final group with Burns, his closest friend, who got back into the mix with a 62. His year has been marked by close calls at the US Open and British Open, but Burns has no victories to show for it.
"It's always a little weird just because I want him to have success so much and I think he wants the same for me," Scheffler said.
"Tomorrow we'll go out there and play our game and see where things finish up at the end of the day. It will be competition like normal."
Im shot 67 and is tied with Burns at 11-under 199. The next closest to Scheffler is Tommy Fleetwood (68) and Jake Knapp (67), both five shots behind.
Adam Scott (69) is the best-placed Australian, eight off the pace at five under and tied for 13th, while Min Woo Lee (75) is three over.
Jordan Spieth gave himself another Sunday at the TPC Southwind. He is at No.54 in the FedEx Cup, and only the top 50 advance to the BMW Championship next week in the FedEx Cup playoffs.
The top 50 is the magic number this week because those players are assured of getting into all the $US20 million ($A28 million) signature events next year.
"That signature series, it's where you want to be," Brian Harman, who came in at No.65 and shot 69 to be in a tie for sixth, said.
"It's where the best golf is played. I'd love to have a chance."
He at least is in all the majors next year from his 2023 British Open victory at Hoylake.
Scheffler didn't get a birdie until the par-3 eighth, but then got hot early on the back nine to restore his lead and also made a 12-foot par save on the 15th.
"I holed a few of those today. It was definitely important to keep the momentum in the round," Scheffler said.
Burns and the No.1 player in the world have only played a final round together at the 2021 Tour Championship, though Burns did beat Scheffler with a long birdie putt in a playoff at Colonial in 2022.
"Scottie ... he's not going to lay down so you're going to have to go out there and put a really good round together and see if you can catch him," Burns said.
With AAP.
