Winning a World Golf Championship event would easily be the biggest victory of Brendon Todd's career but it won't be easy with a host of PGA Tour stars hot on heels before the final round of the St. Jude Invitational.
Todd started Saturday with a two-stroke lead and finished it one stroke clear after five birdies and four bogeys in a one-under 69 left him at 13-under 198.
Byeong Hun An of South Korea, who had four straight birdies on the back nine, finished with a 66 on moving day at TPC Southwind to be second at 11-under par.
"It feels like a practice round out there," An said, with crowds locked out due to coronavirus protocols.
"There's not many people watching and definitely was kind of a relaxing day, I think. I didn't get really tensed up."
Rickie Fowler carded a 69 to be third at 10-under while defending champion Brooks Koepka (68) is a shot further back.
Thomas, who can become No.1 in the world with a victory here, rose to fifth at eight-under after a 66.
"It was nice to shoot four-under on that back nine to give myself somewhat of a chance," Thomas said.
He won on this course in 2018 before the event became a WGC event last year.
Phil Mickelson (66) and Louis Ooosthuizen (68) were in a group five strokes behind Todd.
Jason Day eagled the par-5 16th and birdied the 17th to recover from a tough front nine to share 10th at six-under.
His 69 on Saturday was matched by fellow Australians Marc Leishman (joint 29th), Matt Jones (tied 53rd) and Lucas Herbert (shared 56th) while Cameron Smith (71) dropped to a tie for 67th.
Todd is aiming to secure a fourth career victory and third this season after two wins in November.
This is the 35-year-old American's second 54-hole lead since the PGA Tour's return to play in June, although he faded to finish 11th on that previous occasion.
"I'm excited to be in this position and feel like if I can go out there and swing a little better and keep this putting momentum going, I'll be in good shape," he said.