Hearts chairman George Foulkes has warned that Tynecastle Stadium could still be sold, despite a decisive vote against the plan by shareholders.
Vladimir Romanov hopes to take over at Tynecastle
More than 70% of the votes cast at Monday's extraordinary meeting were in favour of prospective owner Vladimir Romanov's proposal to prevent the sale.
But Foulkes said: "We still need guarantees that he will take over the debt and provide working capital.
"If he can't come up with the money, we either sell or go into administration."
Foulkes stressed that Romanov must prove at meetings this week that his plan for Hearts is viable and acceptable to the club's creditors.
"We clearly now have a decisive vote by our shareholders," he said.
"Seventy per cent of them want us to scrap the deal with Cala to sell Tynecastle stadium for house building.
"Mr Romanov is having discussions with the bank, other creditors and other people involved in Scotland and we expect to hear from him in the next day or so what arrangements he proposes to keep the club financially sound.
"Once we get those details we will then be able to confirm the decision of the shareholders and cancel the deal with Cala."
Hearts chief executive Chris Robinson, who set up the £20m deal to sell Tynecastle for housing development, was the victim of vitriolic abuse at Monday's meeting of around 400 shareholders.
But Romanov, who hopes to complete his takeover in February - with Robinson's 19.8% stake, received a standing ovation.
Romanov had called for the extraordinary meeting, urging the club to abandon plans to sell Tynecastle Stadium to wipe out its debts.
Robinson wanted to hire the nearby Murrayfield Stadium while a site for a new stadium was found.
"Circumstances are changing rapidly and, at the end of last week, it seemed as if an adjournment was needed and that was the view of Mr Romanov, the Bank of Scotland and the Hearts board," said Foulkes on Monday.
"But it became clear that, when Mr Romanov arrived here at Tynecastle and asked for a meeting with the board before the agm, things could be taken forward more quickly.
"We welcome that because the last thing we want is a long period of uncertainty.
"The guarantees are not yet in place, but we did get an indication from our meeting that he expects them to be in place within the week."
Foulkes denied the board were gambling on the club's future by possibly scrapping the Cala deal before an alternative financial plan for the club's future is finalised by Romanov.
"I can't tell you if Mr Romanov has the financial wherewithal to see this through, but I have found him a man of his word," he said.
Former Hearts player and anti-sale campaigner Gary Mackay wants Romanov to sack Robinson and said: "He has to be told by Mr Romanov that he simply cannot stay on. It would be an absolute nonsense if that was allowed to happen."
Robinson told the Edinburgh club's annual meeting that cash from this season's Uefa Cup run would be used to cut debts instead of helping head coach John Robertson strengthen the team.