Amir Khan needed just 76 seconds to defeat Dmitriy Salita in the first defence of his WBA light-welterweight title in Newcastle.
Salita was floored by a lightning-fast left-right combination after just 10 seconds and never recovered.
The New Yorker clambered to his feet, but his legs had gone and the referee had no choice but to step in as Khan continued his bombardment.
Khan, 22, now has 22 wins and 16 knockouts from 23 professional fights.
“It was very explosive, it was just what we asked for,” Bolton’s Khan told BBC Sport.
“We had too much firepower for this guy. After the first shot I could see his legs buckling.”
The 27-year-old Salita was unbeaten in 31 fights going into the fight, and he was expected to at least make a contest of it at the Metro Radio Arena.
But Khan jumped all over him from the opening bell, sending Salita to the canvas with a ramrod left followed by an irresistible overhand right.
Salita was still jelly-legged when Khan renewed his attack, and the American was hurt by a spiteful left and sent back-pedalling into a neutral corner.
Salita was forced to take a knee, and while he was brave enough to get back to his feet, Puerto Rican referee Luis Pavon eventually decided to call a halt to proceedings less than halfway through the opening round.
Khan may now choose to fight in the United States, where he has had his training base since his defeat to Colombia’s Breidis Prescott last September.
That defeat, which seemed career-threatening at the time, saw him team up with legendary American trainer Freddie Roach, and Khan has looked a different fighter ever since.
“Freddie is like a father figure to me and just having him in the corner gives me so much confidence,” added Khan.
“It was a blessing in disguise what happened to me against Prescott - I’ve come back stronger and now I’m a world champion and a world champion defender.”
Khan defeated Mexican legend Marco Antonio Barrera in March, before stepping up a weight and claiming the WBA light-welterweight crown with victory over Andriy Kotelnik in July.
Khan will now help Manny Pacquiao prepare for Floyd Mayweather at Roach’s fabled Wild Card gym in Los Angeles, after which he will weigh up his options.
There has been talk of a match with Manchester’s former light-welterweight king Ricky Hatton, while Dagenham’s Kevin Mitchell, who looked classy in defeating Prescott on the Newcastle bill, has made no secret of his desire to fight Khan somewhere down the line.
BBC Sport - Amir Khan knocks out Dmitriy Salita in first round
