His career looked more likely to be written off than resurrected. The last time he was spotted in training gear was at Murray Park with Rangers. All things considered, no-one has ever signed for Celtic with a backstory like Gordon's.
He has the distinction of being new manager Ronny Deila's first signing, having agreed a two-year contract with the option of a further 12 months. But might he have been a Rangers player instead? "Not really," said the goalkeeper. "They talked about [an offer] a little bit but that's done now. I want to look forward to what I'm doing here. There is a lot of things going on at Rangers and I don't think that I was high on their priority list. They offered me training facilities. I was grateful for that. They have got me back to this point.
"It's slightly ironic, I know, for me to end up here but it's a great opportunity to get back playing at a club playing at the highest level and fighting to get into the Champions League. This is by far the biggest club I have ever played for."
Whatever the opposite of match sharpness is, Gordon has it. He has not played a senior game since a 2-2 draw with Sunderland against Bolton Wanderers on April 28, 2012. A knee injury seemed to have sunk the career of one of the most talented and professional Scotland players of the past decade. It is satisfying to see him back in football properly, and if he returns to the form he showed for Hearts, Sunderland and his country, before injury, Celtic will have signed an excellent and experienced talent for next-to-nothing. In 2007 Sunderland paid £9m to take him from Hearts but his fine performances on Wearside were derailed by serious injuries: he twice broke an arm and then suffered the knee problem which finished him there.
The big imponderable now is whether he can return to his previous level. "I want to play as many games as I possibly can," he said at a Lennoxtown media conference yesterday before he flew out to join the rest of the squad at their Austrian pre-season camp. "I have not been told anything [about whether I will be first or second choice] and I've not asked anything.
"To be here at all is an achievement. It's a fantastic club to be joining after the injury nightmare I have had. I'm going to work as hard as I possibly can to play as many games as I can. I came close to the point where I thought I might never play again. I had to work very hard and put in a lot of hours that will hopefully stand me in good stead once I get back into full training and playing games."
Now, at 31, he faces two duels: with Fraser Forster to be the main goalkeeper for Celtic, and with Allan McGregor and David Marshall to be the first choice for Scotland. The former contest might be resolved soon enough, of course, with Atletico Madrid considering an £8m move for the England squad goalkeeper. Gordon - the old Gordon, at least - would be a ready-made replacement for Forster who seems highly likely to leave, if not for La Liga then the Barclays Premier League.
As for Scotland, Gordon's international career has been frozen on 40 caps since 2012. It once seemed likely that he might nudge close to a century of appearances. Instead he faces a major battle to unseat McGregor and Marshall. "I have never hidden the fact I would love to get back playing for Scotland again. But we will see. I need to get back playing and stay fit before I get back in. But that is an aim."