It’s not over till the fat lady sings.
About this proverb...
It’s not over till the fat lady sings. – actual quote: “The opera ain’t over ’til the fat lady sings†[Dan Cook, KENS-TV sportscaster, San Antonio, TX] — One of the meanings of this proverb could be… Don’t assume a winner until the game is over. (This is an American proverb)