CELTIC'S crippling inability to take a lead and hold it has proved to be their Achilles' Heel in Europe this season.

In Salzburg, they appeared to have found the perfect solution: when pulled back, score another. However, for a second time, they allowed a lead to slip through their fingers, although Jonatan Soriano's stunning free-kick 12 minutes from time was unstoppable.

Wakaso Mubarak, with only his third touch in a Celtic jersey since arriving from Rubin Kazan last month, had put Ronny Deila's side ahead early in the first half. But just as in Warsaw and Maribor, they struggled to settle on that lead, and an equaliser from Brazilian striker Alan sent the teams in level.

Only in the two ties against Reykjavik have Celtic managed to keep the back door shut in Europe. Sure, it's a side still trying to gel and devoid of any real depth of experience at this level, but this is a basic skill they must learn quickly if this Europa League campaign is not to join their Champions League qualification programme as a half-dozen series of matches to file under missed opportunity.

Thankfully, after missing all of the previous European games this season through injury, Celtic can now call upon their inspirational captain, Scott Brown, to dig them out of a hole. He did just that with a speculative 26-yard drive on the hour mark which found the net with the help of a deflection from the outstretched leg of Andre Ramalho.

Celtic goalkeeper Craig Gordon did his best to make that was a winner, but he could do nothing when Soriano's stunner flew into the postage stamp corner.

Having been criticised for gambling with Jo Inge Berget's debut in the away game against Legia Warsaw, it would have been understandable if Deila had played safe in this one. But he threw in Mubarak for his debut on the left, the Ghanaian winger having returned too late from international duty last week to figure in the weekend match against Aberdeen. The move paid off within 14 minutes as Mubarak collected a square pass from Kris Commons 18 yards out and bent a low shot beyond the despairing reach of Peter Gulasci in the Salzburg goal.

However, when it came to firepower, there was still a stark contrast between Celtic and a Salzburg side clipped of their Red Bull wings as UEFA do no permit such branding in the competitions they oversee.

The squad which Deila was able to take to Austria could boast between them a total of 11 goals in all European competitions outwith qualifiers and play-offs. Soriano, now has 13 himself - seven in last season's Europa League run, which made him the top scorer in that campaign. Alan, with his first-half equaliser, briefly matched the tally of the prolific 28-year-old Spaniard.

The unfortunate aspects of Alan's goal was, firstly, the slip by Jason Denayer as he moved to intercept Kevin Kampl's through ball, then the deflection off Efe Ambrose when the Brazilian's shot appeared to be covered by Gordon. The goalkeeper had already frustrated Salzburg with a clutch of fine saves, the best by far of which was a finger-tip diving effort to claw the ball round a post from Ramalho's header.

Before 10 minutes had elapsed in the second half, Alan had twice more been thwarted by Gordon, and Marcel Sabitzer also saw a good shot pushed away by the in-form keeper. While the Austrians were creating the majority of the chances, Deila's side were not entirely toothless. However, they tended to snatch at their chances, no-one more so than Brown when put through by Callum McGregor in the first half. Stefan Scepovic was unmarked in the centre, but the captain elected to shoot and pulled his effort well side.

The Serbian striker had been selected to lead the attack, Anthony Stokes' poor goals return at this level condemning him to a watching brief from the bench until he replaced him mid-way through the second period. The physical presence Deila hoped Scepovic would provide did not materialise, to the obvious annoyance of Brown.

It was always going to be a tough start to Group D for Celtic, facing the section's top-seeded side on their own patch, where Salzburg have harvested so many good results. Their only two defeats this season were in their Champions League qualifier in Azerbaijan against Qarabag, then again when they went to Sweden to face Malmo in the play-offs.

So Celtic will already be looking forward to becoming reacquainted with Salzburg when they come to Glasgow on match day five in late November.