Supercars boss James Warburton has warned Victorian motorsport could face a future with Phillip Island as the category's only championship event with fresh doubt over the future of the Sandown and Winton races.
Amid renewed speculation over plans to sell the Sandown site, Warburton said it was "inevitable" the historic venue would cease to be a motor racing facility and the search was already underway to a find a new location for the Bathurst lead-in event.
Supercars' contract at Sandown Raceway ends this year and the series is negotiating to extend their deal for another three years, which officials expect to see out the venue's motor racing days.
But there remains the threat that the site, which sits on valuable land owned by the Melbourne Racing Club, could be sold off or redeveloped at any time.
The Sandown negotiations come as Supercars' three-year deal to race at Winton in country Victoria is also up for renewal, with Warburton suggesting the event was going to need more government support if it was to continue.
Support from the State Government for a proposed street race in Geelong has not been forthcoming, meaning the events could be lost interstate or overseas.
Warburton said he was resigned to losing Sandown as a Supercars venue, but said the chances of the event staying in Victoria if the site was sold at the moment were slim.
"It's inevitable at some point that venue will cease as a motor racing facility," Warburton said.
"We believe there will be at least another two, possibly, three more years. But after that, the value with the land and the location and all those elements will mean that it won't be an option for us on the calendar.
"I would have thought that Victoria would be fighting to say, 'We want Sandown or we want the 500km race which has a lot of heritage to it before Bathurst and Gold Coast and we want to hang onto it', but I've got no doubt as it currently sits that will be going to another state.
"I think with what's been built in other areas interstate plus our international expansion plans ... it could be down to literally Phillip Island (in Victoria)."
This year will mark the 47th time Sandown Raceway has hosted an Australian Touring Car/Supercars event - the most of any venue around the country.
Alongside rounds at Phillip Island, Winton and Sandown, Supercars also race at the Australian Grand Prix at Albert Park, but it is not part of the championship, which remains an ongoing fight for the series.
The Winton track underwent a significant upgrade with resurfacing over summer, but Warburton said more needed to be done to bring the overall facilities "up to scratch".
"We don't promote that event, that is something that is done by Winton Motor Raceway itself, it's a small body," Warburton said.
"You can see through the government grant they've spent a lot of money in terms of the track upgrade, but their facilities really need to be upgraded further ... Winton is definitely going to need some government support.
"We'd be keen to continue, but realistically, a small organisation like that is going to need support to continue to promote major events like us."