In another extraordinary display of longevity, 46-year-old Scott retained 27th spot in the season-long points race after opening the second FedExCup Playoff event with a two-under-par 68.
Rory McIlroy, Americans Gary Woodland, JJ Spaun, Chris Gutterup and two-time US Open champion Wyndham Clark set the early pace with opening six-under 64s at the BMW Championship in Missouri.
Japan's Ryo Hisatune is solo fifth after firing a first-round 65.
Only the top 30 players in the points race after the penultimate event will qualify for the $US40 million Tour Championship, which Scott won in 2006.
Fellow Australian Min Woo Lee is also well positioned, despite dropping from 18th to 22nd after opening with a one-under 69 in St Louis.
McIlroy got the improved display he had demanded from himself after labouring to an eight-over finish at last week's St Jude Championship, where Scottie Scheffler coasted to victory.
The world No.2 had admitted a positive display again at Bellerive would 'feel like a win'.
It has been a run of frustrating performances from the back-to-back Masters champion, who had returned to action in Memphis for the first time since he tied for 40th at The Open.
McIlroy, though, showed signs of getting back into his groove as part of the early afternoon wave, with birdies at the fourth and then on eight to turn at two under.
A fine tee shot on the par-three 13th then left the Northern Irishman to roll in a seven-foot putt and he picked up another shot following a lengthy drive on the 492-yard 15th.
McIlroy - sitting 13th in the play-off standings and who is assured of making  the 30-man season-ending Tour Championship - continued his momentum to finish with successive birdies and sign for a welcome 64.
"I felt at least like I got myself back going in the right direction, and what I wanted to do with my swing, but still you never know when you turn up here," McIlroy said on the Golf Channel.
"This golf course sets up a lot better for me than Memphis did last week. You can miss it a little bit off the tee, and the playing corridors are a lot wider, so you can get away with it, which I needed to get away with it a couple of times today."
World No.1 Scheffler had been in fine form last week with a final round of 66, but was soon slumped at the other end of the leaderboard after a run of four bogeys through the opening seven holes at Bellerive.
The defending champion recovered a stroke heading into the turn but finished his round with a two-over 72.
with PA
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