European Tour-based Papadatos, from New South Wales, is one of six Australians already guaranteed a place at Royal Portrush when the UK major returns to Northern Ireland for the first time since 1951.

This week, though, the European Tour's Scottish Open offers three more Open spots, while in the US the John Deere Classic affords one.

Having missed the cut in his past five events in Europe, 28-year-old Papadatos will lean on former World No.1 Day's ex caddie Reardon when the 148th Open Championship starts July 18.

Reardon became available in June when Day hired Tiger Woods' former caddie, Steve Williams, full time.

Queensland native Reardon says big-hitting Papadatos – who has won professional tournaments in three countries – has a demeanour suited to golf's biggest stage.

"He's a very talented golfer," Reardon told AAP. "I think he has right mindset for a major; he doesn't get too excited or emotional. He's looking forward to giving his first major a crack."

Papadatos secured his major championship debut via last year's Australian Open, which is part of the Open qualifying series, where he finished second at The Lakes in Sydney.

RIGHT: Reardon caddied for Day for two years. PHOTO: Richard Heathcote/Getty Images.

Reardon, Day's close mate since high school, was on Day's bag for four majors during their near two-year partnership.

He says that experience will benefit Papadatos, who is managed by former NRL star Braith Anasta's growing Searoo Sports agency.

"I can bring a level head to Dimi's bag, which is crucial at a major" said Reardon, who caddied for Day during his PGA Tour win at last year's Wells Fargo event.

"I've also got some experience and knowledge of how golfers at the top go about their work.

"Obviously, Jason was World No.1 for 51 total weeks and he does things that work well for him. I learned a lot from him."

Day, craving a second major to go with his 2015 US PGA Championship, will arrive at Portrush for practice this weekend.

It will be his second major with Williams, the New Zealander who was on the bag for 13 of Woods' 15 major wins – as well as Adam Scott's victory at the 2013 Masters at Augusta.

Joining Day and Papadatos at Portrush are countrymen Marc Leishman, Scott and Cameron Smith, as well as youngster Jake McLeod – whose Open berth came from winning the Australasian Tour's order of merit.

However, 10 Australians are teeing up at the Scottish Open, while four are in action at the John Deere Classic, including former winner John Senden.

- Evin Priest, Australian Associated Press