Celtic saw their perfect start to the new Scottish Premiership season come to an end in remarkable fashion on Sunday afternoon, as the Parkhead outfit slipped to a shock 2-0 defeat to St Mirren on the road.

That dismal result not only saw the Hoops taste defeat in the top-flight for the first time in 38 games, but it also handed a real boost to their Old Firm rivals Rangers, with the Ibrox side now only two points behind in the table.

Such an underwhelming performance away in Paisley had been a far cry from the imperious display that Ange Postecoglou's side had produced in the Glasgow derby just two weeks earlier, with it having been something of a sour way to head into the international break.

The former Yokohama boss was seemingly left to rue his decision to shuffle his pack for the meeting with Stephen Robinson's side, having insisted that he potentially got it "wrong" by making six changes from the side that had secured a draw against Shakhtar Donetsk just a few days earlier.

Having rested a handful of his star names, the 57-year-old handed a rare chance to some of those in reserve, having previously lauded the depth of his squad following the completion of nine major deals over the summer.

One of the peripheral figures who failed to take their opportunity was summer signing Aaron Mooy, with the Australia international having been hooked at half-time after failing to make an impact in the centre of the park.

As club legend Stiliyan Petrov suggested, the 32-year-old was perhaps suffering from a lack of game time in that disappointing 45-minute outing, with his only other start so far this term having come in the League Cup triumph over Ross County.

The experienced asset notably failed to make a single tackle or interception in that limp first-half showing, while also offering little attacking thrust as he also failed to make a single key pass from his 59 touches, as per SofaScore.

The former Brighton and Hove Albion playmaker had looked "sloppier" than most, in the words of Petrov, as a result of his limited role in the early weeks of the season, notably failing to track his man in the build-up to the home side's opener.

Pundit Charlie Nicholas also suggested that the 5 foot 9 gem has looked 'off the pace' when he has featured so far this term, albeit with the 52-cap man unlikely to be afforded the game time he needs to get up to speed.

With European and domestic commitments to juggle in what is a hectic schedule over the next month or so, Postecoglou would likely have been looking to the likes of Mooy to make an impact when he needs to shuffle his pack, albeit with the title-winning coach perhaps concerned that his fringe assets aren't of the quality of the usual starters.

When club action does resume at the start of October, it would seemingly be a shock to see the £4.5m-rated man - who is yet to register a goal or an assist in nine games so far this term - still in the starting lineup, having done little to warrant an inclusion last time out.