Confidence breeds success, they say, and Ange Postecoglou's Celtic are certainly feeling confident.

Who wouldn't be after four consecutive victories and 16 goals scored? 

The Parkhead manager will be after more of the same when Dutch side AZ Alkmaar come to town on Wednesday night for the first leg of their Europa League qualification play-off tie.

Here, The Celtic Way delves a bit deeper into the Eredivisie side ahead of the match.

How have AZ fared this season?

AZ have played one competitive game - and lost it. The Dutch league began at the weekend and RKC Waalwijk, expected to be fighting against survival, defeated AZ, third last season, 1-0.

The match was notable for AZ's blunt dominance. Their xG value for the match was 1.99, they hammered in 16 shots on goal, enjoyed 71.22 per cent of possession, made more recoveries (79 to 65) and won more duels (113 to 92). But they couldn't score. Well they did actually, twice in fact, but both were disallowed.

Celtic have, of course, also experienced matches when they are well on top throughout but can't get the job done. And it was the first match of the season so there's not a massive amount to rely on from it, but it's nonetheless an encouraging match for Celtic in the sense that AZ could be relatively low on confidence as a result.

Prior to their league opener, AZ emerged from a heavy pre-season friendly schedule of nine matches in just over a month with six wins (over NEC, Oss, Panathinaikos, OFI Crete, Real Sociedad and Torino), two draws (against Genk and Anderlecht) and a defeat (to RB Leipzig).

How are they expected to line up?

Throughout pre-season AZ chopped and changed formations but their most-used system is 4-2-3-1. That was also the shape they used 60 per cent of the last campaign but, even then, they had a tendency to mix it up and have variously played 3-4-3, 4-4-1-1 and 4-4-2 over the past year.

Hobie Verhulst will likely start in goal even though he is not expected to be the club's number one for the season. He joined from Go Ahead Eagles last term and played just twice - one full game and one eight-minute cameo as a substitute when he conceded twice in a 4-4 draw with Sparta Rotterdam. Peter Vindahl has been drafted in and is included in the squad for Parkhead but it is unclear whether manager Pascal Jansen will put him straight in as Postecoglou done with Joe Hart against FK Jablonec.

In front of him the back four of Yukinari Sugawara, Timo Letschert, Bruno Martins Indi and Thijs Oosting played the whole match against Waalwijk and started together in the club's final pre-season friendly against Torino. Oosting is a midfielder by trade but is covering the left-back slot while Owen Wijndal recovers from a groin injury.

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In midfield, a name familiar to many on these shores is Jordy Clasie. The experienced former Southampton and Feyenoord man missed a large chunk of last season with pubitis but is back fit for this campaign.

Clasie started the match against Waalwijk alongside Tijjani Reijnders, a squad player from last term, but both were replaced (Reijnders after an hour, Clasie after 74 minutes) in favour of last season's regular central pairing of captain Teun Koopmeiners and Fredrik Midtsjo. Given AZ's surprising loss, it would not be a shock to see Jansen opt to start even three of those four.

Further forward, AZ have lost a couple of mainstays from last season (more on that later) meaning the attacking midfield and striker berths are less easy to predict.

Indeed, so far in pre-season and their league opener, Albert Gudmundsson has regularly featured up top despite being a natural winger. On the flanks, Jesper Karlsson and Zakaria Aboukhlal have started recently - with the caveat being the former is suspended for the first leg and Jansen could decide to go for a traditional striker in recent signing Vangelis Pavlidis with Gudmondsson moving wide.

Who are their main danger men?

Koopmeiners poses an intriguing issue. Despite his deep-lying starting position, the 23-year-old is a persistent scoring threat. Last season he struck 17 times (12.78 xG) including eight penalties and laid on seven assists (4.27 xA) even though he was occasionally shifted into the back three whenever AZ decided to change formation.

Those impressive numbers came off the back of two seasons in which he progressed to the AZ captaincy - during 2019-20 he posted numbers of 16 goals (14.09 xG) and three assists (3.52 xA), gains on the season before when he registered nine goals (6.8 xG) and no assists (2.27 xA).

Output like that doesn't go unnoticed, however, and the build-up to the Celtic game - and the season, really - has been interrupted by reports he would be leaving the club amid interest from the likes of Arsenal and Atalanta.

Celtic Way:

The midfielder - who won a call-up to the Netherlands squad for Euro 2020 but did not feature - admitted recently that the transfer speculation was piling extra stress on him and appeared to hint he does intend to move on if possible.

"This situation is very stressful, because at the end of the day I think about it constantly," he said in quotes reported by Glasgow Live. "If the transfer doesn’t happen before the start to the season I’ll just have to play well and put the most minutes into my legs.

"I know people think I’ve bid the club farewell some time ago, but especially in these times, with the coronavirus and all, a farewell can only take place once the signatures are in place."

What are some weaknesses in their game?

While last season was an exciting, impressive one for AZ they have lost some key players and have spent pre-season trying to recover from that.

In a dilemma Celtic fans will be oh-so-familiar with, AZ have problems between the sticks. Last season's number one Marco Bizot left for Stade Brest which has so far resigned them to playing without an established first-choice.

Winger Calvin Stengs, a consistent creative outlet for AZ last term with seven goals and six assists from the right wing, has departed for OGC Nice along with 15-goal striker Myron Boadu, who has gone to Monaco. Right-back Jonas Svensson, meanwhile, left for Turkish side Adana Demirspor.

Celtic Way:

In addition, Netherlands international left-back Wijndal is still returning to fitness meaning AZ really do not have any option there beyond Oosting. Given he is an attacking midfielder, James Forrest or Liel Abada enjoying regular one-v-ones could be a tasty proposition for Postecoglou, such is his emphasis on isolating his wingers against full-backs.

That said, AZ did invest some of the reported £15million fee they received for Boadu. They recruited forward Pavlidis from Willem II, goalkeeper Vindahl from Nordsjaelland, right-back Aslak Fonn Witry from Djugarden and brought back centre-back Martins Indi, who had been on loan last season, from Stoke City.

But in terms of minutes played last season AZ are missing five of their 11 most-used players from last season through transfer or injury (seven if we count Karlsson and Koopmeiners, though it's likely the latter will play given the importance of the match while the former will surely return for the second leg). That's a lot of continuity issues to try to overcome in such a short space of time, never mind when faced with a rampant, reinvigorated Celtic in front of a capacity home crowd.

It is not, then, unthinkable that rapid, intense football - such as the type Celtic have proven capable of under Postecoglou recently - could very well undo this unfamiliar AZ team amid the pressure of a midweek Parkhead atmosphere.