Billy Joel Concert -- Booze, Blood and Broken Bones

For one concertgoer, when Billy Joel sang "I love you just the way you are" ... the way he was ... was bloody.

Ari Ganales claims in a new lawsuit ... he and his wife were enjoying the show at Madison Square Garden when some wasted rowdies began fighting ... again, this is a Billy Joel concert.

Ganales says one of the hooligans pulled him over a seat and thrashed him mercilessly -- breaking his arm, nose, ribs and causing other severe injuries.

He and his wife are suing MSG ... blaming the Garden for over-serving booze.