Jason Day will need to equal his best finish since The Masters at this week’s BMW Championship if he is to both extend his PGA TOUR season and lock up a place on the Internationals team for December’s Presidents Cup at Royal Melbourne.

Jason DayOne of just three Australians still in the running for the FedEx Cup, Day enters the BMW Championship at Medinah Country Club in Chicago outside the top 30 in the FedEx Cup standings and having just parted ways with caddie Steve Williams.

After just one top-10 finish in six starts together Day and Williams agreed to part ways following Day’s missed cut at The Northern Trust, friend and fellow professional David Lutterus to carry the bag at Medinah.

Now ranked 22nd in the world, Day slipped out of the top eight automatic qualifiers for Ernie Els’ Internationals team this week but can rectify that and earn a place at the Tour Championship if he can finish fifth or better at the BMW Championship.

Starting the week 50th in the FedEx Cup standings, a solo fifth or better would provide the 31-year-old with the points required to move into the top 30 and ensure he doesn’t miss the Tour Championship for just the second time in the past 10 years.

Host to the 2012 Ryder Cup, Medinah hasn’t hosted a full-field event since the 2006 US PGA Championship, Day completing 18-hole practice rounds on both Monday and Tuesday to familiarise himself with the layout.

Although it has been 13 years, there will be fond memories for Adam Scott to draw upon as he was tied for third in 2006, six shots behind Tiger Woods.

Given he has already secured his position at East Lake in Atlanta next week on the back of his top-five finish in the opening week of the playoffs, Scott told AAP’s Evin Priest that he can adopt an aggressive mindset in pursuit of his first win in more than three years.

"It's rare we play with this kind of freedom," said Scott, who enters the second week of the playoffs in 14th position.

"There hasn't really been a tournament where there was no downside to being really aggressive; not that I can remember.

"It's a completely free week. I can absolutely go for it; just attack and see what happens."

The only Aussie to record a win in this PGA TOUR season to date, Marc Leishman, dropped from 12th to 16th in the standings following his missed cut at Liberty National Golf Club but is also guaranteed a spot at the Tour Championship.