Here’s a good one: Al Singer was a good enough fighter to knock out the long-reigning world lightweight champ of four years Sammy Mandell in the opening round of their 1930 world title fight. Mandell had previously beaten Tony Canzoneri in defense of his title. Canzoneri himself got another title try, this time against Singer and knocked him out in the first round, making Singer the first world champ to win and lose his title by first round kayo.
Good shout that one, Jel. Beat me to it. Mandell was a great fighter. Jackie Paterson splatted Peter Kane in the first and I've not checked properly to see if anyone has mentioned Kingpetch getting flattened by Ebihara.