Mentel always grateful working with Man City keepers Given, Schmeichel
The youngster worked alongside stars like Shay Given, Joe Hart and Schmeichel during his four years at Eastlands.
And he hopes that will help him push countryman Dusan Pernis for a starting slot at Tannadice in the new campaign.
He said: "My time at the club was tremendous. I was training with guys like Shay, Joe and Kasper and you can't buy that kind of experience.
"It is great for any player to train alongside keepers of that calibre. You learn all your life and I picked up so much from them. Given has played over 500 games in the English top flight while Hart has played so many matches at the highest level already.
"Schmeichel is also starting to make a big impression and he's only 23.
"I studied them all in training and used to watch their preparation on matchdays. I wasn't shy at asking for advice and they were all approachable and helpful.
"The lads were consummate professionals and their attitude to football was first class."