Celtic recorded their first competitive victory of the Ange Postecoglou era by beating FK Jablonec 4-2 in the Europa League qualifiers on Thursday - but now is not the time to stand still. 

The rebuilding job Postecoglou is fronting is still very much in the foundation stages.

Seven new signings have arrived this summer, with some immediately challenging for first-team football and others already seemingly well down the pecking order.

With more reinforcements surely in the offing - as well as some of the current squad potentially departing - we look at Celtic's current squad depth, identify some 'problem' positions and hypothesise who could come in to strengthen Postecoglou's hand.

Depth chart

Celtic Way:

A cursory look at the squad depth chart could lead you to believe Celtic are well stocked in most positions. Any fan will argue that is not the case. Well stocked in terms of raw numbers does not equate to a deep squad, rather a bloated one.

Indeed, there are a couple of players not referenced in this squad depth chart but who are still listed in the first-team squad - goalkeeper Conor Hazard and midfielders Luca Connell, Scott Robertson and Kerr McInroy - which takes the total number to 34.

Players whose names are in yellow are so as it's unlikely, or at least unclear, that they will be contributing many first-team minutes this season barring serious injury issues. Players whose names are in red are those heavily reported to be leaving in this window or the next.

There are, of course, several players who could be listed in a couple of different positions. For instance, Kyogo Furhashi has already featured as a central striker and left winger in his two appearances since joining, while James Forrest has switched between wings and Ryan Christie has featured wide.

In defence, the abundance of yellow names perhaps points to why supporters have such a lack of confidence in the quality of the personnel currently available.

Of those listed, Christopher Jullien, Karamoko Dembele and Mikey Johnston are currently injured.

Problem positions

Let's take these one at a time. The signings of Joe Hart and James McCarthy mean goalkeeper and defensive midfield are not the problem they were just a short time ago. Likewise, there's unlikely to be a new face at left-back unless one of Greg Taylor or Boli Bolingoli were to depart.

So we begin with a position Celtic have known needed to be strengthened since January: right-back.

Anthony Ralston's unlikely return to the first team may be borne out of necessity but nobody could ever question his commitment. His quality is another matter though, and it also must speak to some degree about Lee O'Connor's shortcomings that he has managed just 41 minutes - all coming in pre-season friendlies - since Postecoglou's arrival. 

It really is as simple as pointing out that Jeremie Frimpong and Hatem Elhamed left the club eight months ago and have not been replaced. At all.

Centre-back is an odd one. Carl Starfelt has been recruited and will surely partner Jullien when he is fit. While Stephen Welsh's fine pre-season appeared to have pushed him into the role of able deputy, Postecoglou's decision to persevere with Nir Bitton at centre-back at his expense suggests another new recruit is being sought.

Eighteen-year-old Dane Murray performed as well as he could after being forced into action after Bitton's sending-off against FC Midtyjlland but he will not be expected to pick up many minutes this campaign. Summer signing Osaze Urhoghide featured in a few pre-season friendlies - at right-back as well as central - and looked like he still has plenty to learn before seriously challenging for a first-team spot.

In central midfield, Liam Shaw and Ewan Henderson also clocked minutes during pre-season but will have a task on their hands even just to deputise for Callum McGregor, such are the new captain's combination of influential and technical qualities.

READ MORE: Nir Bitton has let Celtic down too many times and Stephen Welsh's absence is baffling - Amy Canavan

On the wings, fitness appears to be the main concern. Mikey Johnston has missed considerable game-time due to groin and knee injuries and once again finds himself on the sidelines this campaign after picking up a hamstring problem against Bristol City in pre-season.

Dembele also went off injured in the same match, putting a halt to his impressive start to life under Postecoglou. The manager is no stranger to giving youngsters minutes if he feels they can contribute in his system - Liel Abada's quick-fire introduction shows that - and it seems like 18-year-old Dembele was in line to be given chances early in the season.

"He has been here for a while and I guess he gets an opportunity now," Postecoglou said of Dembele in pre-season. "I think the way we play will suit him. 

"He has been in and around the first-team squad for a little while now. I think he wants to break through and be a first-team player so I see no reason why anybody needs to protect him from that.”

Four strikers are listed on the depth chart, but they all come with caveats. First, Odsonne Edouard has been far from his best for a while now and is expected to leave at some stage (though quite when that will be is anyone's guess).

Furuhashi played well centrally and scored against FK Jablonec but it is unclear whether he will be consistently chosen to lead the line or be utilised wide. The Japan international has indicated he would like it to be the former, though, and Postecoglou sounds like he will give him that chance regularly. 

"I think he’s a threat there," the Celtic boss said after the Jablonec game. "He’s quick, he’s got really intelligent movement and he’s got good finishing."

Elsewhere, Leigh Griffiths has not been spotted since polarising the crowd in last month's pre-season loss to West Ham. Albian Ajeti is the most physically robust of Celtic's striking options but, with Postecoglou's emphasis on constant motion in order to create options for passes, the style does not seem to bode well for the Swiss striker's chances of breaking into the first XI.

Potential solutions

Celtic have been linked with plenty of players this summer, maybe even more so than usual.

For the right-back berth, a deal for Antwerp's Aurelio Buta appeared to be all but done a few days ago but the deal seems to have stalled at the personal terms stage. The 24-year-old possesses superb speed - something that could certainly be useful defensively as well as offensively in Postecoglou's system - and has a reputation for being a useful, varied crosser but the fact he has not played many full 90-minute matches is a potential concern.

Alternatively, or in addition to if Postecoglou is really lucky, the Hoops have been linked with Independiente full-back Fabricio Bustos. The 5ft 6in 25-year-old has featured in central midfield as well as right-back, which could be an attractive trait for the Celtic boss given the added responsibilities he places on full-backs in his system.

Centrally, defender Ben Davies was close to a £2million move to Glasgow back in January before Liverpool came calling as they fought off an injury crisis. The 25-year-old is reportedly back in the frame for a move north but a loan deal may not be what Postecoglou is looking for at this juncture.

Highly-rated Shamrock Rovers defender Liam Scales is another target. With the 6ft 4in left-footer capable of playing centrally or out left, he appears to fit the mould of what Postecoglou values - the only question is if he is at the level required to come to Parkhead and contribute straight away. As the squad depth chart shows, there are already several players who aren't quite ready to do that so another one would add little to the equation.

St Johnstone captain Jason Kerr has earned plenty of plaudits for his displays at the heart of the Perth side's defence and those were ramped up on Thursday night as he scored a penalty in a famous 1-1 draw against Galatasary. His defending appears to hold up statistically with his ability on the ball the main drawback.

Elsewhere, Manchester City defender Ko Itakura looks set to leave the Etihad and could add something to the Celtic ranks. He has one year left on his deal and played all 34 matches while on loan at FC Groningen last season as the club finished seventh and qualified for Europe.

The 24-year-old - an international team-mate of Furuhashi's - may not be a ball-carrying defender in terms of driving out from the back to break lines but he is comfortable with the ball at his feet (he played 50 passes per game last season with 91% accuracy and only 4.86 of those being long) and has steady interception stats (5.74 per game).

READ MORE: Why Kyogo Furuhashi should be exciting Celtic fans and how Greg Taylor's inverted run carved open Jablonec - Video

In central midfield, Kerr's Saints team-mate Ali McCann has received even more attention for his performances. However, while certainly a talented player, scouting reports suggest he may well be better playing alongside McGregor rather than deputising for him, given his style of play.

On the wings, there is every chance Christie features there regularly as long as he is at the club while Furuhashi could find himself there often as well. Even with Johnston and Dembele fit the wide berths could do with reinforcements, however, and one name that keeps cropping up is Kristijan Lovric.

The 25-year-old Croatian has become something of an internet sensation among Celtic fans after following the club on social media and liking its posts. A left winger, Lovric has an eye for goal and struck 17 times in 29 games for Hungarian side Gorica last season.

That said, he overperformed in front of goal (12.35 xG) while virtually matching his expected assist total of five (4.99 xA). Stretch those measurements back to take in the last five seasons and Lovric has performed above scoring expectations consistently (scoring 52 goals, 38.31 xG) while falling short of them creatively (17 assists, 21.2 xA).

It would remiss not to mention the progress of Owen Moffat, too. The left winger already impressed Postecoglou with a goal against Sheffield Wednesday during pre-season and hit the ground running in Celtic B's Lowland League campaign, including netting a quite sensational long-range lob against Stirling University. The 19-year-old's attitude has also been called "first-class" by captain McGregor but this season's rebuild may come just too soon for the academy graduate to make the step up.  

Last, but certainly not least, the main name being bandied about for the potential striker's berth available when Edouard leaves is a familiar one: Kevin Nisbet. 

The Hibernian forward knows where the goal is, as they say. His raw totals were impressive in the lower divisions with Raith Rovers (34 goals in 46 games) and Dunfermline Athletic (23 in 32) while he took to the top flight instantly last season after moving to Easter Road (scoring 14 with an xG of 13.98).

His form dipped after a move to English side Birmingham City broke down in January but Nisbet still managed to net twice against the Hoops and finished behind only Edouard in the Premiership scoring stakes. He also received a Scotland call for the Euros ahead of Griffiths. 

Nisbet appears to have started this season with renewed vigour and, while he did not find the net in Hibs' league opener against Motherwell, he nonetheless impressed with his touch and attempts to link up play.

No matter what avenue Celtic choose to go down, the depth chart alone shows there are still some key decisions left to be made if Postecoglou is to make his vision for Celtic a reality.