Yeah I bet that is it. Though I did not even know that the film was based on a book until I looked it up on IMDb. There is also the remote possibility that it could be The Cincinnati Kid another film that I did not know was based on a book [by Richard Jessup] until looking up the film on IMDb.

How mortifying. I posted this without looking at the second clue from Daithi. Of course it had to be the Hustler!