They were given a heartfelt round of applause from their supporters at the end.
European football for Celtic after Christmas will almost certainly depend on them avoiding a three-goal defeat at home to Anderlecht next month after they lost to goals from Kingsley Coman - the consequence of a bad mistake by Dedryck Boyata - and Javi Martinez, despite a fine late strike by the impressive Callum McGregor. "My family will be delighted and it's a big reward for them for believing in me and putting the work in all these years".
This isn't to say Tierney should leave Celtic at the first possible opportunity.
Leaving Robert Lewandowski and Thomas Muller in Germany as a precaution ahead of a vital Bundesliga clash with Borussia Dortmund on Saturday, Heynckes said: 'I changed the team because I had to take into account the players' conditioning and their training. There's a certain quality to the way he whips the ball into the box from wide areas that is Gareth Bale-esque.
Celtic Park has long been known as the ground which is immensely popular with visiting footballers, with the Bhoys fans regularly whipping up a frenzied atmosphere intended to intimidate away teams and put fire in the bellies of the home side. Kieran Tierney, fresh from signing a six-year contract, won midfield possession with typical tenacity before feeding James Forrest.
"We've got to deal with it. We got good pressure on the goalkeeper, positioning is good on our defensive line and we've got to head it, it's as simple as that", the Celtic manager said.
Napoli currently sit top of Serie A but they badly need a result against City if they want to progress to the knock out stages of the Champions League.
They all starred in the Celtic side that had a brilliant UEFA Cup run, after failing to reach the Champions League losing a play-off to the Swiss Champions Basel.
Yet it was enough to lift the crowd, with Bayern not really threatening Craig Gordon.
Moussa Dembele then tore at the German defence.
Replays were inconclusive as to whether Coman was guilty of using an arm. Why the devil not! 'I'm more disappointed we didn't deal with the header. Hardly a Celtic game passes without a scout from one English club or another spotted in the stands.
Both players required treatment for head knocks, but it was Celtic who were groggier having harboured hopes of going on to win the game for just three short minutes.