The Southampton ace spent two years at Celtic until 2014.
Fraser Forster has told The Glasgow Evening Times that he keeps in regular contact with former Celtic team-mates Scott Brown and James Forrest.
The England goalkeeper left Celtic to join Southampton in 2014 after two impressive years at Parkhead.
The 29-year-old could come up against the duo on Saturday when the Three Lions travel to Hampden Park for a World Cup qualifier with Scotland.
And Forster revealed to The Glasgow Evening Times that it will be an odd experience if he faces some of his old Hoops colleagues
“I know quite a lot of the lads and it’ll be a bit strange for me as it’s probably the first time I have faced most of them since leaving Celtic,” he said.
“We had a great group of lads when I was there, folk like Joe Ledley, Gary Hooper and Charlie Mulgrew as well. We had such a togetherness within the squad and that was fantastic. If you’ve got that it makes life on the pitch a lot easier.
“I still speak to them quite a bit, especially Scott and Jamesie. It’ll be a strange one. When they have been your team-mates for so long and then you head back to Scotland to face them, it’ll be great to see them.”
Brown and Forrest are two of six Celtic men in the squad to face England, with Craig Gordon, Kieran Tierney, Stuart Armstrong and Leigh Griffiths also included.
The Bhoys’ contingent will go into the clash on something of a high after enjoying a phenomenal season in the Scottish Premiership, with manager Brendan Rodgers masterminding a domestic treble – without losing a match – in his first year in charge.
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