Unleashed (2005)

Also known as: Danny the dog (Hong Kong: English title)
This is the story of Danny, a slave who has lived his whole life without any sort of normal human education, with the mind and personality of a young child, with only one lesson learned: how to fight. Treated like a dog by his owner/boss, Bart which includes having to wear a collar, Danny has been raised to be a lethal fighting machine who fights in illegal gladiator-style fight clubs, where he earns lots of money for Bart as the undisputed champion. After a car accident that lands Bart in a coma, however, Danny meets a kind elderly blind piano tuner on the run because he knows secrets some bad guys don't want known, who uses music to teach Danny some things about the world and about being human...
Main actors are: Jet Li as Danny, Morgan Freeman as Sam the piano tuner, and Bob Hoskins as Bart.
imdb.com/title/tt0342258