Celtic manager Ange Postecoglou has got little wrong in his Parkhead tenure thus far, sparking a rapid rival at the Old Firm outfit after the doom and gloom under his predecessor Neil Lennon.

Having guided the Glasgow side to the league title in his first full season in charge last term, the previously unknown quantity has again been earning rave reviews in the early weeks of the new campaign, following the Hoops' imperious form thus far domestically.

One key factor in the 56-year-old's success to date has been his astute business in the transfer market, with the former Yokohama boss scouring the globe to find a raft of hidden gems who have since gone on to blossom.

That being said, not every new addition has made a stellar impact for the Premiership champions under the Aussie's watch, with January arrival Yosuke Ideguchi no doubt one of the rare few who has failed to deliver thus far.

Part of a triple J-League swoop last winter alongside his compatriots Daizen Maeda and Reo Hatate, the Japan international has subsequently gone on to be something of a bystander during his time at the club so far.

The 26-year-old - who previously failed to make an appearance during a brief stint at Leeds United - had been lauded for his versatility and quality after arriving at Celtic, with former Greuther Furth coach Damir Buric dubbing him a "soldier" due to his hardworking nature.

The £675k-rated man has been unable to show that talent over the past eight to nine months, though, having made only six appearances in all competitions under Postecoglou so far, including just three in the league.

That lack of action has largely been caused by injury, with the £15.5k-per-week dud having suffered an unfortunate knee issue just a matter of weeks after joining the club, while he is also yet to feature so far this term.

Although the midfielder cannot be blamed for his injury absence, it is no doubt telling that he has been excluded from the club's 25-man Champions League squad, with new acquisition Oliver Abildgaard one of those to earn an inclusion at his expense.

In truth, it is hard to see where Ideguchi goes from here even once he returns to full fitness, with pundit Alex McLeish previously suggesting that it will take a "minor miracle" to get his Hoops career back on track, while also suggesting that the player's "days are numbered" at the club even at this stage.

While there is still time left for the former Gamba Osaka man to reverse his fortunes - with four years still remaining on his current deal - at present his capture appears to have been something of a disaster for Postecoglou and co.