Buuxi weedha soo socota: Mertens wuxuu dalbaday billad kale oo guuleystayaal ah 22kii Diseembar 2014 ka dib markii Napoli ay ku guuleysatay toogashada ganaaxa Juventus ee Supercoppa. In kasta oo inta badan loo isticmaali jiray bedel ahaan, wuxuu sii waday qaabkiisa wanaagsan ee Napoli inta lagu gudajiray xilli ciyaareedkii xigay iyo badh, isagoo dhaliyay 10 gool wuxuuna gacan ka geystay 11 caawin dhammaan tartammada 2014-15, iyo 11 gool oo dheeri ah
2015<unk>16. Xilli ciyaareedkii dambe wuxuu ka mid ahaa taageero ku saabsan guushii ugu weyneyd ee Napoli ee horyaalka Europa League, guushii 5-0 ee kooxda reer Belgium ee Club Brugge. Mertens wuxuu sidoo kale dhaliyay hat-trick qeybtii labaad guul 6-0 ah oo uu ka gaaray Bologna 19-kii Abriil 2016.