I remember the term as being popularized in the 1970s, in regard to the Washington Bullets' chances of winning the NBA championship. I thought that it was the c

I remember the term as being popularized in the 1970s, in regard to the Washington Bullets' chances of winning the NBA championship. I thought that it was the coach who coined it, but Wikipedia says not. Anyway, Wikipedia traces the expression "The opera ain't over till the fat lady sings" no farther back than the middle 1970s. The Ring Cycle had a fair bit of history by then; and I'm not that confident in the ability of guys in the 1970s sports world to name the soprano roles in opera.