With Troy Parrott and captain Jordy Clasie back from injuries but unable to start, 21-year-old Mexx Meerdink earned his eighth consecutive start as AZ's lone striker as the Alkmaar side were looking to lock up a spot in the second qualifying round of the UEFA Conference League.
Manager Maarten Martens' decision to start Meerdink, even though the youngster had scored just three goals since returning from injury in March, paid off quickly as the striker opened the scoring after a mere three minutes. Meerdink doubled his tally in the 21st minute with a near-identical goal.
AZ took the foot off the throttle after the 2-0, seeing as though Heerenveen were hardly able to put any pressure on the home side, but still saw Meerdink complete his hat-trick before the break, completing his triple with a header from a Seiya Maikuma cross.
AZ, who Tottenham Hotspur eliminated in the UEFA Europa League's round of 16, widened the gap via Portuguese centre-half Alexandre Penetra, who patiently waited at the back post for a corner and smashed the ball in in the 66th minute.
Substitute Ion Nicolaescu put a Heerenveen goal on the board after converting on a perfect Mats Kohlert cross, but it was all the visitors could muster in another tough outing away from home.
AZ progressed to Sunday's play-off final, which will be played in their own AFAS Stadion against either FC Twente or NEC Nijmegen.
View all the match statistics on Flashscore.
