Michael O'Reilly, of Ruanbeg Manor, Kildare, Co Kildare, along with his brother Martin and Martin's partner Claudia Reiss, of Portarlington, Co Laois, claim they own a 20pc stake in a racehorse called Tashzara.
The horse's brother Excelebration is one of the fastest horses in the world.
In proceedings against building contractor Edward Logan Jnr and his wife Edel Logan, of Grangeclare, Kilmeague, Co Kidare, the three are seeking an injunction preventing the horse from being offered for sale at Goffs Bloodstock sales tomorrow and at Tattersalls in England in early December.
The court heard that in correspondence from solicitors for Mr Logan, it was denied that he (Mr Logan) is the owner and that Mrs Logan owns Tashzara.
It was also denied that the three plaintiffs have a share of the horse.
The plaintiffs are also seeking a declaration from the court that they own a 20pc share of the horse. Permission to bring the proceedings was granted, on an ex parte (one-side only) basis, yesterday by Mr Justice Paul Gilligan who made the case returnable today.
Yesterday, lawyers for the O'Reillys and Ms Reiss told the court their clients were given a share of the horse following an oral agreement entered into in January 2009 between them and Mr Logan, who they say is the majority owner of the horse.
For a 10pc share, Michael O'Reilly was to manage Tashzara's affairs. For exercising, grooming, feeding and getting Tashzara ready to race, both Martin O'Reilly, a retired jockey and Ms Reiss were to receive 5pc each.
The court also heard that there was a breakdown in the relationship between the parties over a dispute of fees being paid for another horse they were asked to train and they had not spoken since last June.
The O'Reillys and Ms Reiss subsequently learned that Tashzara was to be offered for sale and claim they had no prior knowledge of this.
In an affidavit, Michael O'Reilly said Mr Logan assured him that if the horse was sold, his and the other plaintiff's "20 per cent was safe." However, he fears the sale would deprive him and the others.