Answer
PSV Eindhoven was the club from which Napoli signed Dries Mertens. The Belgian forward joined Napoli in 2013 after spending four seasons with PSV, where he had established himself as a prolific goalscorer. Mertens quickly became a key player for Napoli, helping the club win the Coppa Italia in 2014 and the Supercoppa Italiana in 2014 and 2015.