Hearts chief executive Chris Robinson has agreed to sell his 19.6% stake in the club to Vladimir Romanov.
Chris Robinson will pocket close to £900,000
Robinson has entered into a conditional agreement to sell his entire beneficial holding for a sum of £866,868.80.
"We believe that in Hearts we have identified a highly attractive opportunity for investment," said a spokesman for the Lithuanian buyer.
Many Hearts supporters will be hoping that Romanov's new investment will prevent the sale of Tynecastle.
The current Hearts board agreed a deal to sell the club's home stadium to property developers Cala Management.
But the terms of the £20.5m deal allows Hearts to pull out of the sale if a financially viable alternative is found before 31 January 2005.
It is also thought that a newly-shaped Hearts board could negotiate with Cala to keep the club at Tynecastle until a new stadium can be built and prevent the scheduled move to Murrayfield next season.
Hearts, who have been based at Tynecastle for 118 years, are currently struggling with debts of around £18m.
"The board of Hearts welcomes the announcement of a significant purchase by Vladimir Romanov of shares in Heart of Midlothian PLC," said chairman George Foulkes.
"If the conditions attached to the sale of Chris Robinson's shares are satisfied and the sale of his shares is subsequently completed and the sale of Tynecastle goes ahead, the club may be presented with a viable alternative to moving to Murrayfield.
"An arrangement with Cala giving Hearts the temporary right to occupy Tynecastle would afford the club the ability to continue to play at Tynecastle until a suitable long term venue is found.
"This would mean that, notwithstanding completion of the sale of the stadium, Hearts would not have to surrender vacant possession of Tynecastle.
"Nevertheless, there are many interests to reconcile in the discussions that lie ahead and shareholders and fans should not at this stage conclude that Tynecastle will necessarily continue as the home of Hearts beyond season 2004/05."
The deal for Robinson's shares is scheduled to be concluded by 8 December and he will then step down from his chief executive role.
Romanov, who has held talks with Dundee, Dundee United and Dunfermline in the past, is a major shareholder in a company which has a holding in mid-sized Lithuanian bank, Ukio Bankas.
He was one of the founders of Lithuanian club Kaunas and remains a member of the board.