Neymar, 27, visited Barcelona but ultimately chose not to appear in court, where he is suing the La Liga champions over an unpaid loyalty bonus.
Barcelona spent much of the close season trying to bring Neymar back to the club two years after he left to join Paris St Germain but on Friday the Brazilian's attempts to negotiate with his old side ended in mutual recriminations.
An agreement to avoid a trial appeared to be close on Friday morning before collapsing at the last minute.
Neymar, 27, visited Barcelona but ultimately chose not to appear in court, where he is suing the La Liga champions over an unpaid loyalty bonus of 26 million euros.
Representatives for both parties presented evidence in their respective claims, although they still have time to reach an agreement before an Oct. 21 deadline to present final written conclusions.
Neymar's presence was not compulsory and only likely in case of a trial, so his absence was initially seen as a sign a last minute agreement deal be reached. But after spending the night in the Catalan city, Neymar left before proceedings began.
Barca, meanwhile, are suing the forward for 8.5 million euros in damages and demanding he reimburses the club for part of the loyalty bonus they paid him in November 2016.
Lawyers for the Catalan club said on Friday that by joining PSG less than a year after penning a contract which tied him to the club until 2021, Neymar failed to comply with its terms.
Lawyers for Barca said in court that the club did not pay the disputed bonus after it became clear Neymar was already in negotiations to join PSG. "At that time it was perfectly clear that the player had no interest in staying in the club," said Barcelona lawyer Carles McCragh.
Neymar's lawyers argue that he began talks with PSG only after the Catalan club failed to make the payment.
Neymar, who scored 105 goals in four seasons with Barca during which he won two La Liga titles, three Copa del Rey triumphs and the Champions League, is no stranger to legal troubles.
In 2016 he was summoned to the High Court in a fraud and corruption investigation over his transfer to Barcelona from boyhood club Santos in 2016.
The player denied any wrongdoing and although charges were later dropped the case has since been reopened.
Neymar was accused in June of raping a model in a Paris hotel room but he said the encounter was consensual and prosecutors dropped the case two months later, citing a lack of evidence.
Neymar missed PSG's first five games of this season as he tried to force through a move back to Barcelona. His former club made repeated trips to the French capital to negotiate a deal, but PSG said the Catalans had failed to meet their asking price.
Neymar has since returned to action for the Ligue 1 champions, scoring in 1-0 wins over Strasbourg and Olympique Lyonnais and playing in Wednesday's 2-0 defeat by Stade Reims.