Liverpool have entered the fray to try and sign Spain international Ruiz, according to the Sunday Express.
Jurgen Klopp and the Reds saw his skills first-hand as Napoli defeated them 2-0 at the Stadio San Paolo and drew 1-1 with them at Anfield in this season's UEFA Champions League group stage.
OK Diario in Spain, however, claim he has a verbal agreement with Real Madrid coach Zinedine Zidane.
Madrid have long been linked with Ruiz, 23, who won player of the tournament as Spain took out the U-21 Euro 2019 title.
He has since stepped up to the senior Spain squad, earning six caps.
Napoli, it's understood, would be willing to take advantage of the situation and part with him for an inflated price to the tune of €80 million (A$145m).
Ruiz emerged at Real Betis, under current Barcelona boss Quique Setien, as one of Spain's most promising young players.
Setien is understood to be a big fan of the midfielder, hence Barcelona's reported interest.
Since signing for Napoli on a reported €30 million (A$54m) deal from Betis in 2018, his stock skyrocketed as he quickly became one of the Serie A's finest centre-mids - even displacing club captain Marek Hamsik in the process.
