Sunderland have launched a £20 million legal claim against a leading law firm in a long-running saga sparked by the botched signing of attacking midfielder, Ricardo Alvarez, from Inter Milan in 2014.
The Black Cats accuse the high-profile legal practice, Mishcon de Reya, of missing a crucial deadline to file an appeal in the case, which had already seen the club pay out to both Inter and Alvarez.
The two parties met at the High Court on Friday, as they prepare for a hearing that is expect to last for a week.
Sunderland argue that by allegedly missing the appeal deadline at the Court of Arbitration for Sport (CAS), which is based in Lausanne, Switzerland, Mishcon denied them the chance to overturn judgements that had already been made and recoup their money.