Five things we learned from Celtic's 3-1 win over FK Sarajevo.

CELTIC ARE STILL WEAK FROM SET-PLAYS

Sarajevo’s opening goal was down to the shambolic nature of Celtic’s marking and the lack of bravery from Odsonne Edouard to put his body on the line to then block the goal-bound effort, and was in-keeping with goals Celtic have conceded in Europe over the last few years, no matter who their manager is.

They were able to recover from this aberration, but manager Neil Lennon will be drilling it into his players that they can’t afford to gift the opposition such cheap goals as the qualifiers progress, as they found to their cost last year in Athens.

He will hope that once the imposing Christopher Jullien is up to speed, he will toughen up Celtic’s soft centre at the heart of their rearguard.

Evening Times:

READ MORE: Johnston gets his timing right to help ease Celtic nerves

MIKEY JOHNSTON HAS SUBSTANCE TO GO WITH THE STYLE

It has the feeling of a big season ahead for the 19-year-old, whose ability has never been in question. His end product, however, has been doubted, but he had an emphatic answer to any critics of his finishing here.

Not only did he prove that he can produce in the final third, but also in the big moments, as his 25-yard stunner hauled Celtic level just as they were rocking a little in the raucous atmosphere that had exploded since the Sarajevo opener.

Johnston was the outstanding player in Celtic’s pre-season tour of Austria and Switzerland, and he stood out again here before being forced off with a knock. A hugely exciting prospect, and Celtic will be hoping the knock he took to his quad is only minor so as not to halt his momentum.

BOLI BOLINGOLI SHOWED HE IS ABLE DEPUTY/REPLACEMENT FOR KIERAN TIERNEY

Until his bow in a Celtic jersey was halted by injury not long after half-time, Bolingoli had shown that he can certainly prove a valuable asset at full-back.

Whether that is as an able deputy to Kieran Tierney once the undisputed number one left-back returns, or whether the £3m signing is viewed as a replacement for Tierney in the long-term should he be prised away, there was enough in this initial showing to suggest that the former Rapid Vienna man can prove a hit in the Hoops.

Evening Times:

READ MORE: Neil Lennon delighted with Celtic's early promise in Sarajevo

There may be something of a sweat for Celtic ahead of the second leg after he limped off before the hour having rolled his ankle, and it would be a blow if the new signing joined Tierney on the treatment table.

NEIL LENNON NEEDS A RIGHT BACK, ASAP

If there is a little less concern over the left-back area now with the arrival of Bolingoli – injury permitting of course – then the same cannot be said on the opposite flank.

Kristoffer Ajer did well in the circumstances considering the central defender isn’t at all accustomed to the role, but there were times when his discomfort highlighted starkly the need for Neil Lennon to bring in a natural alternative as soon as he possibly can.

CELTIC HAVE FORTITUDE

This may have been the first competitive outing for Celtic this season, but it was the third time in four games since the start of pre-season that they have fallen behind. On all three occasions they have recovered to win the game, and while manager Lennon will no doubt prefer his men to start a little sharper, he will be encouraged that they don’t panic or become disheartened when they do fall behind.

Here, there was a real danger that any side could have retreated inside their shells after going a goal down, with the deafening atmosphere all around and the treacherous conditions underfoot, but Celtic steeled themselves. Eventually their greater quality showed.