The international break came at the worst possible time for AZ, who would have been riding high after a famous win away at a struggling Ajax side.
Match preview
While most of the headlines will have centred around Ajax's demise, the performance of AZ in their 2-1 win in the Dutch capital was to be marvelled at.
AZ have picked up something of a knack of beating Ajax at the Johan Cruijff Arena of late, as that victory two weeks ago was their third in their last five visits.
To put that into context of what a fine achievement it is for the club, in their previous 41 league visits, they had only ever won twice - in 1980 and 2015.
Those three points keep AZ within touching distance of a PSV Eindhoven side still maintaining a 100% start at the top.
AZ's only blip came in drawing at home to Heracles Almelo - a game which saw them dominate from start to finish only to be caught out on the break.
Apart from that though, domestically, AZ have been faultless, winning all of their other seven matches so far, putting them in second place.
With AZ already an astonishing 17 points ahead of Ajax, it appears the top four may already have been decided in the Eredivisie, with PSV, Feyenoord and Twente all also making strong starts.
The Eredivisie will get three places in next season's Champions League too as opposed to two, so the race is already on for the top three between those four clubs.
With another huge game against Aston Villa to come in the Europa Conference League next midweek, it has actually been AZ's form on the continent which has threatened to derail their excellent start.
Pascal Jansen's men made a mess of qualifying, scraping past Andorran minnows Santa Coloma before needing penalties to see off Brann.
They then farcically threw away a 3-0 lead away to competition debutants Zrinjski Mostar on matchday one to lose 4-3.
Improving on a pretty underwhelming home record against Heerenveen will be on the agenda first though, because even though a 1-1 draw last season ended a three-game winning run in this fixture, AZ have only won seven of the previous 17 home clashes against these opponents.
Heerenveen have run into a sticky spell of form though, despite starting with two wins from two.
In the six games since, Kees van Wonderen's side have taken just one point, and that came in the game directly before the break against NEC Nijmegen.
De Superfriezen had enough chances to win the game, but Van Wonderen may have just been pleased to arrest such an awful run of defeats.
Those five straight losses saw Heerenveen ship six goals at De Kuip against Feyenoord, as well suffering heavy home defeats to Sparta Rotterdam and Excelsior.
Their next few fixtures away from the Abe Lenstra Stadion make for grim reading too, with this trip to Alkmaar being followed by away matches against Ajax and PSV.
AZ Alkmaar Eredivisie form:
W
W
W
D
W
W
AZ Alkmaar form (all competitions):
L
W
D
W
W
W
Heerenveen Eredivisie form:
L
L
L
L
L
D
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Team News
AZ will hope striker Vangelis Pavlidis can keep up his sensational start to the season, as the Greek international has netted 10 in just eight league games so far.
That marks the fifth consecutive season in which Pavlidis has hit double figures in the Eredivisie, and he is just two goals away from matching his tally from 2022-23.
On the injury front, Jansen is set to be without Mees de Wit with a foot injury and Sem Westerveld, who has a knee issue.
The visitors have a few injury worries heading into this clash, headed by Che Nunnely who is out with a knee injury.
Hussein Ali is also set to miss out, as Van Wonderen may go with a similar side that were unfortunate not to beat Nijmegen.
Ion Nicoleascu may have lost his place in the side to the returning Patrik Walemark recently, but the Moldovan netted twice during the international break, including in a famous draw away in Poland which has remarkably kept the minnows hopes of qualification alive.
AZ Alkmaar possible starting lineup:
Ryan; Sugawara, Bazoer, Penetra, Wolfe; Clasie, Mijnans, De Wit; Lahdo, Pavlidis, Van Brederode
Heerenveen possible starting lineup:
Noppert; Hall, Van Beek, Bochniewicz, Kohlert; Brouwers, Haye, Olsson; Walemark, Van Amersfoort, Sahraoui
We say: AZ Alkmaar 3-0 Heerenveen
Nothing looks likely to stop AZ in their current form, and this should be another routine success before looking ahead to the visit of Aston Villa.