Adam Scott challenged Cameron Smith to step up to the plate if he wanted to earn his way onto Australia’s two-man team for the World Cup in Melbourne in November; now the in-form 25-year-old is determined to shut the door.

As the top 70 players vie to stay in the hunt for the $10 million winner’s bonus on offer for the winner of the FedEx Cup at the BMW Championship this week, the intriguing sub-plot for the four Aussies in the field centres around a World Cup on home soil.

The leading player from each of the top 28 nations on the world rankings became eligible on September 3 but have until September 13 to decide whether they will play or not.

If, as is expected, Jason Day declines due to the birth of his third child days before the World Cup commences at Metropolitan Golf Club, Marc Leishman would become the automatic Australian selection and have his choice of teammate.

Which, given the performances of Smith and Scott in the latter stages of the season, will not be an easy decision to make.

Leishman indicated earlier in the year that he would most likely select the next Aussie in the world rankings and No.32-ranked Smith is determined not to allow world No.39 Scott to make a late play.

"My foot is on the pedal; I still need to make sure of (World Cup selection)," Smith said on the back of consecutive top-3 finishes to start the FedEx Cup.

Which is adding even more pressure on Leishman ahead of his title defence at Aronimink Golf Club.

“Cam is probably in the box seat," Leishman told AAP.

“But I am going to wait until the deadline to give everyone the best chance to get in.

"One good week from ‘Scotty’ and he’s only got to jump eight spots; I’m giving them both as much chance I can.”

With his third-place finish at the Dell Technologies Championship last week Smith leap-frogged Day to be the highest-ranked Aussie halfway through the FedEx Cup Playoffs and ensure his place in the Tour Championship at East Lake for the first time in his young career.

Scott missed both the BMW and Tour Championship last year and needs a strong finish this week to move into the top 30 in the FedEx Cup and book his place at East Lake where he was triumphant in 2006.

Sitting 48th in the standings, Scott is currently 153 FedEx Cup points outside the top 30, meaning that he will likely need to finish well inside the top 20 if he is to advance.

While Scott is the hunter, Leishman is in the group of players who are being hunted as he sits in 22nd position.

Victorious in this event at Conway Farms 12 months ago, Leishman has three top-25 finishes in his past six starts and needs something similar to keep the wolves at bay and wrap up his place at the Tour Championship.