Need help identifying a kung fu trilogy I watched a few years ago.
The plot is like this: There is a very poor chinese kung fu master working at a coal station. I don't really remeber what happens in the fisrt movie, but in the second movie he gets some kind of apartament in a city and teaches a student how to fight against some gang members. In the third film, an american boxer claims that he is stronger than any chinese master, and launches a challange: anyone who could win him in the ring would win.
Any idea which movie is this?