Floyd Mayweather needed just 140 seconds to beat Japanese kickboxer Tenshin Nasukawa in an exhibition boxing bout worth a reported $9m.
Former five-weight world champion Mayweather, 41, was smiling during the short-lived contest in Tokyo as he floored the 20-year-old three times.
The fight, scheduled for three three-minute rounds, ended with Nasukawa in tears as his team threw in the towel.
Despite his latest comeback, Mayweather said afterwards he was “still retired”.
“It was all about entertainment – we had a lot of fun,” said the American, who beat UFC’s Conor McGregor in a boxing match in August 2017. “They wanted this to happen in Japan, so I said ‘why not?'”
The fight was delayed by several hours, with rumours circulating on social media that Mayweather might not show up, and that organisers were struggling to locate him.