Napoli moved top of their Champions League group with a commanding performance against already eliminated Red Star Belgrade as Dries Mertens scored a brace at Stadio San Paolo.
Marek Hamsik put the hosts ahead, volleying in from close range after Nikola Maksimovic's near post flick from a corner.
Mertens doubled Napoli's lead 22 minutes later when he finished past Red Star goalie Milan Borjan from Mario Rui's deflected cross.
Mertens grabbed his second of the night in the second half, netting his 100th Napoli goal to become the club's all time leading scorer in Europe and the first Belgian to reach ten Champions League strikes in the process before Red Star pulled one back through El Fardou Ben.