Tunnicliffe won the FA Youth Cup as a United player alongside the likes of Paul Pogba and Jesse Lingard.
On Pogba, he said: “Everyone can see he is world class. I have played alongside him quite a few times. But to play against him would be quite fun. I'm sure he'd say the same.
“To win the World Cup is something you dream of as a kid so for that to happen to him was amazing but when he first came he was a good lad.
“He was loud but I had been there a while so I just did anything I could do to help him. You could see how good a player he was.
“I knew he would be my midfield partner so we tried to bond and have a relationship off the field and it was nice of him to say what he did about me.
“I think I'm a nice guy and if he thinks I helped him, I'm happy as he has gone on to do great things. If I can take a slight bit of credit for that, I'm happy.
“He's bigger and stronger than he was. I have an idea what I'm up against. But it is up to me to stop him. I don't really have a point to prove. But I was there a long time so it's a big one for me."
The 27-year-old, who had loan spells at Peterborough. Barnsley and Ipswich before leaving United, said: “He has the hair cuts and people want to focus on that.
“People want to find faults, which is wrong, but that is the world we live in. Anything he does is magnified but he is a big enough character and is not bothered.
“I was shocked when he left. He was on the cusp of the first team. But it was not a bad decision as he has won Italian Leagues and Cups and is now back where he started."