And so, the champions stay perfect in the new Scottish Premiership campaign, with Mika Baur's goal proving the difference in Celtic's 1-0 win on Wednesday night.

Martin O'Neill had taken the decision to shuffle his park for the trip to Perth, ahead of the looming Glasgow derby, with it unsurprisingly taking a while for the visitors to get going amid a muted first-half display.

The Hoops were reliant on debutant Sam Johnstone to keep it at 0-0 before the break, following a fine point-blank save from the Englishman, while their own breakthrough didn't come until the 52-minute mark, as Baur prodded home from Haissem Hassan's pull-back.

Positive moments then for many of O'Neill's new signings, although it was the same old story for Sebastian Tounekti. At least he wasn't alone in enduring a disappointing day at the office.

Tounekti frustrates again amid narrow St Johnstone win

With Yang Hyun-jun absent as a result of his looming participation in the Asian Games, the chance was there for Tounekti to grab that vacant left-wing berth, ahead of the meeting with Rangers.

Unfortunately, the clash with St Johnstone was merely more of the same for the Tunisian, in truth, with it set to be no surprise if Camilo Duran returns on that flank this weekend, should Hassan remain on the opposite wing.

Tounekti, while a more natural left-winger, just hasn't delivered enough in a Celtic shirt, previously one of the many to struggle late on amid the desperate collapse away in Linz.

This latest performance wasn't quite so disastrous for the 24-year-old, yet time and again he appeared to make the wrong decision at the key moment, while criticised by Chris Sutton on Sky Sports for playing it "safe" too often in the early exchanges.

To his credit, he kept on trying, but the lack of end product was truly alarming, his dearth of confidence so evident as he opted to pass rather than shoot at one stage in the first half.

When he does elect to run at his man, he has the tools to be a nuisance, but the final ball remains wayward too often, leaving the likes of Kasper Hogh visibly frustrated inside the area.

The statistics say it all, in truth, as Tounekti completed just one of his 12 attempted crosses, lost the ball 22 times from 66 touches and provided only a solitary key pass, with the key intervention ultimately coming from Hassan on the opposite flank.

Not the night Tounekti would have wanted, then, although he wasn't the only one who failed to take their chance.

Celtic star just played his way out of the starting XI vs Rangers

Rotating so extensively was a risk against an improved St Johnstone side, although it did allow O'Neill to hand vital minutes to the more peripheral members of his squad.

Johnstone, as his key first-half save showcased, looks like someone who could genuinely threaten the starting XI, yet the likes of Tounekti and Dane Murray will almost certainly make way this weekend.

In Tounekti's case, he can at least be credited for his dogged determination to keep trying to make things happen, having no doubt been heavily involved even if not everything went his way.

The same, unfortunately, can't be said of new man Oliver Sorensen, the on-loan Dane proving rather anonymous in that advanced midfield role.

It is early days for the Parma midfielder, of course, yet he did little on Wednesday night to suggest he should be pushing for a regular role any time soon, having been a bystander to proceedings prior to his withdrawal on the hour mark.

Perhaps he merely suffered from trying to fill the shoes of Benjamin Nygren, particularly in what looked like an unsuited number ten berth, yet even so, Soresen's lack of involvement really was stark.

Both in and out of possession, the late arrival offered little all night, with it no coincidence that the man ahead of him, Hogh, only truly came alive when Nygren had entered the fray instead.

Sorensen simply didn't get on the ball enough to impact play, offering little in the way of a link between his compatriot and the midfield unit.

That can be seen most notably by the fact that he actually only recorded 23 touches in total, even fewer than the aforementioned Johnstone recorded in the sticks (48).

For context too, his direct replacement, Nygren, also surpassed him after registering 26 touches in just 23 or so minutes.

Rather damningly too, while Sorensen only provided one key pass, Nygren's cameo saw the Swede register five key passes and create two 'big chances', a stark contrast even if the latter man did benefit from the game opening up late on.

Any new addition, as is the way, deserves time to properly bed in to their new surroundings, yet this is a club and a city where first impressions can count for everything. The most concerning part may well be that Sorensen hasn't made one at all.