That’s it. The Tour Championship is here and thus, the end of a very long US PGA Tour season.

It won’t be this long next year, and the Tour Championship’s delivery of the FedEx Cup champion will be far different. (Instead, the FedEx Cup leader will start the season-finale at 10 under par, while the rest of the 30-man field’s scores will be staggered according to their position.)

But in the final year of the current system, here’s all you need to know about what could happen at Atlanta’s East Lake Golf Club this week:

How it works

The top 30 on the FedEx Cup standings after the BMW Championship have advanced to the season finale, the Tour Championship. The top-five seeds are (in order) Bryson DeChambeau, Justin Rose, Tony Finau, Dustin Johnson and Justin Thomas. If one of them wins, the FedEx Cup title is theirs automatically and pocked the $US10 million bonus in addition to the tournament prizemoney. The other 25? They need to win to get a foot in the door, and then have a perfect s***storm among the rest of the field.

Winning scenarios: Aussies

Cameron Smith: 10th on the sandings

‘Smitty’ needs to win at East Lake. Then — according to the convoluted calculations — also have the following to happen:

– DeChambeau finish in a three-way tie for fourth or worse

– Rose finish T3 or worse

– Finau finish in a three-way tie for second or worse

– Johnson finish in T2 or worse

– Thomas finish second* or worse

Jason Day (12th)

JDay needs to win the Tour Championship and have:

– DeChambeau finish in a three-way tie for sixth or worse

-Rose finish fourth or worse

-Finau finish in a three-way tie for second or worse

– DJ finish T2 or worse

– JT finish T2 or worse

Marc Leishman (29th)

‘Leish’ needs to have two more players’ fortunes go his way. Leish needs to win the Tour Championship and have:

– DeChambeau finish 28th* or worse

– Rose finish in a three-way tie for eighth or worse

– Finau finish in a three-way tie for third or worse

– DJ finish third or worse

– JT finish in a three-way tie for second or worse

– No. 6 (Keegan Bradley) finish T2 or worse

– No. 7 (Brooks Koepka) finish T2 or worse

Winning scenario: Tiger Woods

Tiger needs to win and have:

– DeChambeau finish T15 or worse; Rose finish in a three-way tie for fifth or worse; Finau finish T3 or worse; DJ finish in a three-way tie for 2nd or worse; JT finish in a three-way tie for second or worse; and Bradley finish T2 or worse

Winning scenario: FedEx leader DeChambeau

If golf’s mad scientist wins the Tour Championship, he wins the FedExCup, but he has a reasonable chance of winning with a top-six finish and can finish as low as a T29 and still have a chance of winning.

How are the bonus payouts calculated for the top 30?

First place gets $10 million, second gets $3 million and third gets $2 million and the bonus payouts go down incrementally until 30th place gets $175,000.