Golfer Rory McIlroy was on "markedly inferior" commercial terms than fellow golfer Graeme McDowell, the Commercial Court in the Republic has heard.
The big business division of the High Court has also heard that Mr McDowell was a shareholder in Dublin based Horizon Sports Management - which is being sued by Mr McIlroy - at a time when the young golfer was considering appointing Horizon as his management.
Mr McIlroy has no complaint against Mr McDowell personally, the High Court has heard, and the young golfer does not intend to involve Mr McDowell in the hotly contested proceedings.
The "extraordinary revelations" were detailed this afternoon by lawyers for Mr McIlroy who now wants to amend his legal action against Horizon, his former agent.
Barrister Rossa Fanning, for Mr McIlroy, told High Court Judge Mr Justice Peter Kelly that it was represented to Mr McIlroy by Horizon's MD Conor Ridge that he would be on the same commercial terms as Mr McDowell.
Mr McIlroy's claims have been disputed by Horizon who said it was not represented to the Northern Ireland born sports star that he would be on the same commercial terms as Mr McDowell.
Paul Sreenan SC, for Horizon, said that it was represented to Mr McIlroy that he would be on the same terms that he enjoyed with his previous management.
Mr Sreenan also said that a separate vehicle, Gurteen Limited, had been set up to handle Mr McIlroy's interests.
Mr McDowell was not a shareholder in Gurteen, said Mr Sreenan.
Mr McIlroy is due to testify for at least two weeks when the trial is heard next year.
A provisional trial date of Tuesday, January 27, 2015 has been set for the case, which could run for two months.