THERE really is no substitute for a goal-scorer, so Celtic fans better hope Stefan Scepovic's choice of the No.12 shirt is not an omen.

The Serbian finally arrived in Glasgow this week carrying the burden of being the only player to have cost any Scottish club money in the transfer window which appeared not to want to end.

He is also being asked to shoulder the responsibility for adding the finishing touch - literally - to the system Ronny Deila wants to implement.

The lack of an effective striker with power, strength, height and touch has made the transition the new manager has been forcing through, with inconsistent levels of success, falter at some of its biggest hurdles.

In particular, the matches against Legia Warsaw and Maribor served to highlight that - without a Scepovic-type player at the point of attack -there is no cutting edge, and very little end product.

Anthony Stokes was tried there and reminded everyone why he was seldom given that responsibility in European games when Neil Lennon - the man who signed him - was the boss.

Four starts this season have seen the Republic of Ireland striker add exactly no goals to his record in European competition, which now stands at two in 23 appearances.

Teemu Pukki scored twice in the home tie against KR Reykjavik, advancing his career total to seven in Europa and Champions League games.

But the Finn was never going to be the man on whom Deila could build for the future and his departure on loan to Brondby this week confirmed that even a bit-part was not available for the man who has never looked comfortable in a Celtic strip.

The clear-out also included Holmbert Fridjonsson to the same Danish club, while Amido Balde headed to Beveren in Belgium.

With Tony Watt already sold to Standard Liege - his goal against Barcelona when Celtic were a club capable of reaching the last 16 of the Champions League undoubtedly added a few euros to the money the Hoops were able to demand for him - the plethora of strikers at Deila's disposal is suddenly much leaner.

Leigh Griffiths could have joined the aforementioned on the bus to loansville, with Hibs eager to invite him to fire them back to the top flight.

But, given how protracted and unpredictable the quest to bring on board Scepovic became and how traumatic and troublesome signing John Guidetti has been, there was never any chance the man signed from Wolves in January was going to be allowed to leave at this time.

Like Stokes, Griffiths has a seriously good track record for scoring goals, but has a lot to do to be as involved as he might want to be as he struggles to find a role in Deila's plans.

It will be a case of adapt, if they have the ability and the inclination to so do, or become accustomed to watching games - and Scepovic - from the bench.

That's a situation which would undoubtedly lead to growing unhappiness and unrest.

Hovering in the background is the spectre of the court case over analleged assault which Stokes faces in Dublin, and the uncertainty over what action, if any, will be taken against Griffiths when Police Scotland and the SFA complete their investigations into alleged misbehaviour in an Edinburgh pub ahead of a Hearts v Hibs game earlier this year.

The contrast between these two and Callum McGregor could not be more stark.

The clean-cut 21-year-old has grabbed the opportunity given to him by Deila in pre-season, and produced the performances and goals which make him one of the first names the manager puts on his team sheet.

With Kris Commons another established player fighting to command the same sort of involvement as McGregor, the need for someone to step up to the plate and provide the steady stream of goals Celtic must have if this transition is to pick up pace and prove successful, is clear.

In the opening 10 games, they have found the net 17 times. But 13 of those goals came in three matches - against Reykjavik, St Johnstone and Dundee United - when poor defending played a big part.

The more illuminating stat is that Celtic have failed to win six of those games, exiting the race for a Champions League spot and taking just seven points from their opening four league matches, equalling their poorest start in any title race this century.

Though Deila is confident he will make a significant difference, Scepovic alone can't transform this team.

Finding someone who can provide the necessary back-up to the striker could be the key to the season.