'A yakuza gang targets the blind masseur ...'

From the film summary - "A yakuza gang targets the blind masseur Zatoichi after he defeats their group in a wrestling match."

I did not get that at all from the movie. Yes he fights in the wrestling match but I took this as an introduction to Zatoichi himself. There is no mention of the yakuza during the match and no-one ever gives it as the reason for the bounty. Was it explained? Did I turn away during the wrong subtitle? Or was there no subtitle for the explanation that was given (or hinted at) in Japanese?

Most website reviews don't mention (or avoid) the reason behind the bounty, wikipedia simply states the same as IMDb. One spoiler heavy website (http://www.weirdwildrealm.com/f-zatoichi4.html) says that he "angers the local yakuza who arranged the betting on all sports" so I'm wondering if that's the kind of information that would be common knowledge for a Japanese audience, hence no need for an explanation?

[edit] padded out the post