A sponsorship squeeze and budget shortfall could see the cancellation of the only four-star three-day event in the southern hemisphere.
The 2009 Australian International Three Day Event looks set not to proceed this November, said event organiser and dual Olympian Gillian Rolton.
"It's a bitter disappointment, but faced with the financial realities of 2009 we're being forced to make an extraordinarily tough decision," she says.
"Unless an extremely generous benefactor - or naming-rights sponsor - is prepared to come forward with significant financial support, we will have no option other than cancelling this year's event."
The event, scheduled to be held in Adelaide's parklands on November 13 to 15, is the most important horse trials event in the southern hemisphere.
It has four-star status and just last November there was talk that it would try to achieve the new five-star rating when it was introduced this year.
"We're having to make the call now," says Rolton, "because so many of our top class and international riders depend on the Australian International Three Day Event as part of their qualifying and selection path for the World Equestrian Games in Kentucky in 2010, and potentially the Olympics in London in 2012.
"It's only fair we give them enough notice to make alternative qualifying arrangements."
Rolton said the event was also set to host the hotly contested Trans-Tasman Championship with New Zealand, "so its cancellation is a double blow".
The highly regarded event is one of only six four-star equestrian competitions in the world, taking its place alongside Badminton and Burghley in the United Kingdom, Kentucky in the United States, Pau in France and Luhmuhlen in Germany.
The not-for-profit board of Adelaide Horse Trials Management Inc, which runs the Adealide competition, said it was extremely grateful for the ongoing support of all of sponsors, in particular its major partner, the South Australian Government, through the South Australian Tourism Commission as well as the Department of Sport and Recreation, Equestrian Australia, the Adelaide City Council, Adelaide Equity Partners and Channel 7.
Board Chairman Bob Gillen said the 2008 event had been a breakthrough success and plans had been in place to grow the event even further.
"Unfortunately, we're in the same position as many other sporting events and clubs which rely heavily on corporate sponsorship. It's tough out there."
South Australian Tourism Commission chief executive Andrew McEvoy said he was disappointed by the news.
"We have been big supporters of the three-day event since it came to Adelaide's parklands in 1997. It really has added to our events calendar at the right time of the year and it's disappointing that it won't go ahead this year due to lack of corporate support."
Its cancellation would mean the event being staged in only one out of the past three years. The 2007 event was cancelled due to Australia's equine influenza outbreak.