A piece of Willie Mays' historic career is hitting the auction block ... and the winning bid could end up being a fortune!!
TMZ Sports has learned ... Mays' game-worn and autographed threads from the 1969 All-Star Game -- when Mays played for the San Francisco Giants -- are up for grabs via Heritage Auctions.
The No. 24 gray, orange and black jersey features the SF name on the front ... with a sweet John Hancock from the "Say Hey Kid" himself. It also has "Mays 42/3 1969" and the "W.