ATLANTA: It is a numbers game at this week's Tour Championship, with numerals one, three, five and 10 dominating conversation at East Lake Golf Club.

The Sept. 24-27 Tour Championship brings together the top 30 players on the FedExCup points list, but besides the nearly $1.5 million first prize on offer in this fourth and last event of the playoffs, there is much more at stake.

The number one ranking in golf, which now belongs to red-hot Australian Jason Day, is yet again up for grabs.

Day, winner of four of his last six events and five overall in 2015, ascended to that coveted perch atop world golf with his spectacular win at last week's BMW Championship, where he blew away the field.

But the title of golf number one has been passed around like a hot potato between the Big Three of four-times major winner Rory McIlroy, Masters and U.S. Open winner Jordan Spieth and PGA Championship winner Day in recent weeks and this event could settle the issue for the rest of 2015.

Meanwhile, the top five players in the FedExCup list - Day, Spieth, Rickie Fowler, Henrik Stenson and Bubba Watson - can clinch the playoffs title and $10 million bonus should they win the elite Tour Championship event, which begins on Thursday.

Besides those significant numbers, there is also the Player of the Year award at stake in a season where Day's extraordinary finish has set up a duel with Spieth for the coveted award voted on by their PGA Tour peers.

"Of course it's between Jason and Jordan and someone with the first letter of a 'J' will win it," 2013 FedExCup winner Stenson told reporters on Tuesday.

"I would still wait until this week is over before I would put my final vote on that. I think it comes down to what happens this week."

Players Championship and Deutsche Bank Championship winner Fowler, who like Day (27), Spieth (22) and McIlroy (26) is a member of the emerging under-30 set, agrees it is a two-man race for Player of the Year.

"We have a tough decision between the two of those guys," 26-year-old Fowler said on Tuesday.

Stenson, who is without a tournament victory this year, would claim the $10 million prize with a win or by finishing second or third if the other leading contenders finish down the list at East Lake.

"There's no one that's playing great and is sky high on confidence and no one with a bunch of majors and no one hits it 330 off the tee, so it shouldn't be that hard," Stenson joked, in pointed reference to Day, Spieth and McIlroy.

"But if I finish second or third and win the overall, you won't see me leaving here crying. I know that much. Not out of sadness anyway."