The midfielder is set to enter the final year of his contract; this July and so will be available if his suitors meet his price.
Napoli have reportedly placed a £25.8m price tag on the 26-year-old, who joined the Italian giants from Real Betis for £27million in 2018.
The Italians are eager not to lose Ruiz on a free transfer next summer, attracting the interest of Arsenal and Newcastle, as well as Premier League giants Manchester City and Manchester United.
According to the Italian paper, Corriere dello Sport, Newcastle submitted a £42m bid for the Spanish international in January. But the bid was rejected by Napoli, who at that time were still in the title race in Italy and were reluctant to lose their star man. But the Magpies now have the chance to sign Ruiz on a cut-price deal.
However, Newcastle are up against Arsenal, who are now the most interested party according to the Italian newspaper.
The Gunners are in pursuit of a creative midfielder and have been keeping tabs on Leicester star Youri Tielemans. But being that Ruiz comes at a lower price, they may take up the opportunity to sign Ruiz on the cheap instead.
Corriere dello Sport also claims that both United and City have now joined the summer chase as well.
Ruiz, who operates predominantly as a deep-lying playmaker, featured in 32 league matches and scored seven goals as Napoli finished third behind AC Milan and Inter in Serie A last campaign. He mostly played alongside Andre-Frank Zambo Anguissa in a double-pivot or midfield three at Napoli last season.