Sydney - Jordan Spieth has another tough act to follow at the Australian Open. 

Spieth won the tournament in 2014 in his first appearance Down Under when it was played at The Australian Golf Club in Sydney. He won it again in 2016 in a playoff at Royal Sydney, a year after finishing tied for second with Adam Scott and a shot behind winner Matt Jones at The Australian.

Beginning Thursday at The Australian, Spieth will attempt to make it three Australian Open titles in four appearances. Jason Day, playing back home in Australia for the first time in four years, is his major opponent. 

Spieth won the Masters and U.S. Open in 2015 and Day won the PGA Championship. Both players were also within one shot of a three-man playoff in the British Open that year. 

They are playing together in Australia for the first time. 

"The 2015 season was a lot of fun," Spieth recalled on Wednesday. "The last three majors of the year, we both had a chance to win on championship on Sunday. That's rare to have a few times in a row, especially two people to have the chance." 

Spieth will look to win his third Stonehaven Cup without caddie Michael Greller, who has been on the bag in all 14 of the Texan's professional wins, including three majors. 

Greller has decided to stay in the US with his wife Ellie after the October 13 birth of their son, Barrett. Spieth's long-time coach, Australian Cameron McCormick, will be his caddie for the tournament. 

Scott will be missing his national championship for the first time in a decade. 

"There were some communications and discussions had and unfortunately we couldn't reach an agreement with Adam," tournament director Trevor Herden said. 

Australian fans will get to see Scott at at next week's Australian PGA Championship at Royal Pines on the Gold Coast in Queensland. Masters champion Sergio Garcia and Marc Leishman are also playing at the PGA. 

After Day and Spieth, the Australian Open field becomes very thin. It has only two other distant major winners - 2006 US Open winner Geoff Ogilvy and 2003 Masters champion Mike Weir, along with a host of veteran and younger Australians. 

"It's a disappointing situation when Adam Scott's not playing the Australian Open," Ogilvy said. "You can find blame or whatever ... but we've got a pretty good field. Most golf tournaments would fall over themselves to get Jordan and Jason in their field, so that's pretty good." 

Day, a former No 1 who has slipped to 12th after going winless in 18 months, will play with Ogilvy and Rod Pampling in a morning start on Thursday. 

Day has packed on some weight - he is about nine kilograms heavier than he was at the start of this year. 

"Unfortunately I think I was doing the wrong things in the gym," Day said. "I got a little too big in the upper body and it restricted my (swing) turn." 

Spieth will join Jones, who has played as a member at The Australian since he was 15, and fellow Australian Cameron Smith in an early afternoon group. Smith was among the three-man playoff last year at Royal Sydney when Spieth won his second title. 

"To get into the playoff and be so close, not a good feeling," Smith said Wednesday. "I had a bit of a heavy heart for a few weeks. "