Dalton Smith became Britain's latest boxing world champion after knocking out Subriel Matias in the fifth round in Brooklyn to claim the WBC super-lightweight title.
Smith extended his unbeaten record as a pro to 19-0 when a right hook dropped Puerto Rico's Matias and the referee called for the stoppage, despite Matias attempting to get to his feet.
The Sheffield fighter had rocked his opponent with another right hand earlier in the same round.
Smith suffered a cut over his left eye in the fourth round which the referee ruled came from a headbutt.
Speaking after his huge win at the Barclays Centre, the 28-year-old said: "Listen, it's the first time in my career I've been the underdog and the first time I've fought a monster.
"Take nothing away from Subriel - he's a great champion. I didn't really stick to the tactics tonight. I played him at his own game. You can't hurt me and I knew I'd get to him.
"This is a message to every kid out there. Do not let anybody tell you can't achieve your dreams because if you work hard, you can do it.
"Bring on the challenges. I'm one of the best, if not the best in the division. I'm ready to mix it up with everyone."
Smith joins compatriots Fabio Wardley (heavyweight), Lewis Crocker (welterweight), Jazza Dickens (super-featherweight) and Nick Ball (featherweight) as a current male world champion.
A homecoming fight could be next for Smith, with promoter Eddie Hearn saying: "Smith has announced himself as the light-welterweight superstar. The future is unbelievable.
"Now, fighting at Hillsborough (Sheffield Wednesday Football Club's ground) is a reality."
Smith's debut fight on American soil was in danger after Matias tested positive for a banned substance last November, but it was decided a month later that the 33-year-old was not guilty of violating the drug policy.
Matias' uppercuts and combination punches challenged Smith early on but the Brit rallied as the dethroned champion was knocked out for the first time and saw his record as a pro dip to 23-3.
In Matias' 23 victories, 22 have come via knockout.
