Under a revamped "staggered start" format to the PGA Tour's lucrative season finale, Thomas will automatically tee off on 10 under at East Lake Golf Club outside Atlanta.
The "Starting Strokes" format introduced this week is designed to eliminate the confusion of past FedEx playoffs, when the winner of the final tournament was often different from the series champion.
Instead, the 30-man field at East Lake have been given starting totals which reflect their performances this season.
Put simply, the player who finishes on top of the leaderboard this week will also pocket the $15 million prize on offer to the FedEx Cup champion.
Thomas, who captured his 10th career title with a win at the BMW Championship on Sunday, is now in pole position at the top of the leaderboard.
Patrick Cantlay will start in second on eight under, while Brooks Koepka will tee off in third place on seven under.
Patrick Reed starts on six under with Northern Ireland's Rory McIlroy fifth on five under.
Despite the unusual position of starting the tournament with a lead, Thomas insists he will not be thinking about defending his advantage at the top of the leaderboard when this week's event gets under way.
"It's going to be tough," said Thomas, who could join Tiger Woods as the only man to win two FedEx Cup Championships after his victory in 2017. "I'm just going to have to try to play another golf tournament and act like everyone's staring at zero and try to shoot the lowest 72 holes," added Thomas.
McIlroy, the 2016 FedEx champion, who will start five shots off the lead this week, believes Thomas can take a conservative approach into the tournament on the 7,346-yard par 70 layout.
"If I was in JT's position, it would be, 'OK, I'm going to go out and shoot 67 every day. No one should beat me if I do that,'" McIlroy said. "I think you have to just control what you can."
Thomas meanwhile admits he will be grappling with the unknown.
"There isn't a person on the planet that's experienced this before, for the stakes it's for," Thomas said. "I'm just going to try to deal with it the best I can."
The format for the FedEx Cup finale has not been universally popular, with many critics taking aim at a qualifying system that has no mechanism for allowing the inclusion of 2019 Masters champion Tiger Woods and British Open winner Shane Lowry, two high-profile absentees this week.
PGA Tour commissioner Jay Monahan defended the format, emphasising that the final 30-man field was designed to reward consistency over a whole season.
"We are in the Playoffs, and Playoffs inherently bring forward a lot of volatility,"Monahan said.
"I think what it says is that, one, it's really hard to get to Atlanta and the Tour Championship. You've got to play exceedingly well over the course of an entire season, and with volatility, there's risk.
"And if you don't play well over the course of the season or you don't get off to the start that you envision at the start of the playoffs, you take the risk that you're not going to be here.
"I want to emphasize the fact that what Tiger and Shane did this year, those are two of the greatest stories of the year. So would you want them here? 1,000%.
"But you look at every other sport and their playoff format, and you'll have top teams that fall out early. You'll have some things that you may not have predicted, particularly at the moment when they won those two big events."