The Pole, who has struggled with injuries, notched up three goals between the third and 38th minute of the match against Belgian side Genk.
The Poland international slotted in his second in the 26th minute and then converted a penalty in the 38th.
Napoli won the game 4:0, securing a place in the last 16 of the Champions League.
The Italian side finished as runners-up in their Group E on 12 points, one behind Liverpool.
(pk)
Source: PAP