A trip to the Stadio San Paolo to face Napoli is a very tricky way for Liverpool to begin the defence of their Champions League crown. 

With an inevitably thunderous atmosphere providing a backdrop, Liverpool must stifle the threats of Dries Mertens and Lorenzo Insigne in attack while attempting to breach a defence led by the excellent Kalidou Koulibaly.

In midfield, there will be an opponent Jurgen Klopp knows all too well in Spain international Fabian Ruiz. Liverpool, along with Barcelona and Real Madrid, have been keeping tabs on the 23-year-old, who has cemented his place as an integral part of Carlo Ancelotti's set-up.

Sportsmail provides all the info you need on a player who has caught the eye of Europe's heavyweights.