Pundit Pat Nevin reckons Neil Lennon 's favoured 3-5-2 Celtic formation could be put back into cold storage in the wake of Thursday's spirited fightback against Milan.
The Hoops boss decided to switch things up at half-time and the return to the 4-3-3 worked as Moi Elyounoussi scored to put the Serie A leaders on the ropes before a stoppage time strike sealed a 3-1 Europa League win for the viistors.
The decision to switch to a three-man central defence was forged in Dubai and that system helped Celtic to secure a ninth consecutive Premiership title.
But the Martin O'Neill favourite - a formation Lennon thrived in as a player - hasn't yielded the same success this season with the Hoops struggling for performances even more than results.
And Nevin is certain is certain the time is now to freshen things up again ahead of Sunday's crunch clash with Aberdeen at Pittdorie.
Speaking to 5 Live, he said: "When you are playing three at the back and you can't get through teams, that's why Celtic fans are asking the question.
"I don't think that three at the back is going to last much longer for Celtic.
"With the personnel they've got, they are much better getting in another midfielder and letting the creativity flourish.
"Neil Lennon at half-time said 'c'mon, we're having a go now', they did have a good a go.
"Being freed up, going four at the back, get more midfielders, getting creative players on, let's go!
"Suddenly, you are 10 feet tall like and that's what they played like in the second half."