Rory McIlroy is uncertain if the new format of the Tour Championship will help establish the FedEx Cup finale as an elite competition comparable to golf's four majors.

Justin Thomas will take a two-stroke lead into the end-of-season tournament at East Lake after the format was altered.

Instead of a points reset for the Tour Championship, players will start on different scores – with Thomas, who claimed a three-shot win at the BMW Championship - top of the 30-player leaderboard before the event begins on Thursday.

Though McIlroy sees the benefits of the new format, the four-time major winner is unsure over if the rule change is the best way to improve the prestige of the Tour Championship.

"If the FedEx Cup wants to have this legacy in the game like other championships do, is people starting the tournament on different numbers the best way to do it?" McIlroy said in a news conference.

"That's my only thing. I get it from a fan experience and giving guys who have played better through the year an advantage, but at the same time, I don't know.

"It'll make it sweeter for a guy who starts at even or one-under-par and goes through all the field and wins. Come back to me on Monday and I'll tell you whether it's worked or not."

McIlroy will start in fifth on the leaderboard, with Patrick Reed (-6), Brooks Koepka (-7) and Patrick Cantlay (-8) between the Northern Irishman and Thomas, who is at 10 under.

"Everyone's goal coming into this week was to be on that 10-under mark," added McIlroy. "Obviously, JT is there and there's a couple of guys between myself and him.

"It's a different format this year, it's more the psychology of it. I'm starting five back, but it's very different. We're all creatures of habit and it seems very different that you're starting at a different position to the rest of the field.

"At the same time, you have to just control what you can, play the best golf that you can and hopefully if you play four good rounds then that's the lowest number at the end of the week.

"In past Tour Championships, guys from 15 to 30 had a chance to win the Championship but not really the FedEx Cup. I think those guys have a much better chance this week. I can see a scenario where 15 guys have a chance to win the entire thing.

"It'll be exciting, it'll be different, but you've just got to go out there and play good golf, not look at what other guys are doing and trust that by the end of the week things will even out."