Undefeated three-division champion Terence “Bud” Crawford emphatically stamped his place in the history books with a ninth-round TKO over the previously unbeaten Errol “The Truth” Spence Jr. to become the first undisputed welterweight champion of the four-belt era in the SHOWTIME PPV main event Saturday night from T-Mobile Arena in Las Vegas in an event presented by Premier Boxing Champions.