The Gavin & Stacey actor will play the main role in One Chance, a film based on the life of original Britain's Got Talent winner Potts.
Corden is said to have tried out six different sets of expensive false teeth for the role yesterday (October 9), reports The Sun.
Film producer Harvey Weinstein allegedly flew over from the US in order to make sure the correct teeth were chosen for the part.
A source said: "James spent six hours in the dentist's chair at Ealing Studios with an army of people chipping in.
"The full make-up and wardrobe team had a say, with the director, producers and exec producers offering their thoughts.
"He filmed a full camera test ahead of filming kicking off next week.
"It's such a key part of the project to get right. Paul Potts is a distinctive-looking bloke, and his face is so well known in the UK, they have to get it spot-on."
One Chance is scheduled to begin filming in Venice next week.
Director David Frankel recently told Digital Spy that Simon Cowell may play himself in a cameo role in the film.