Forster re-signed for the Hoops this week and is now competing with the same goalkeeper who was brought in as his replacement back in 2014.
Prior to joining Celtic, a serious knee injury threatened Gordon's career, and the Southampton loanee is blown away that the 36-year-old is still competing at such a high level.
He told The Scottish Sun: "Football can be pretty mad. It’s just swings and roundabouts all the time. What Craig did was fantastic. To come back after being out for two years and just play at all was impressive.
“But to then compete at the level he has done is ridiculous."
Bringing Forster back to Parkhead was essential.
Scott Bain has dislocated hit thumb, putting him out of action for a month, but even before that the former Dundee man was struggling in a big way.
The Scot, who signed for Celtic 18 months ago, had a horrendous start to the season and didn't cover himself in glory during the Champions League exit to Cluj earlier this month.
But Forster already has high stock among the Bhoys faithful and if all goes to plan, Bain won't be getting his place back when he returns.
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